attack

Heroic cats

dr. dolittle — Fri, 16 May 2014 17:04:43 +0000

Heroic cats

Just in case you have not seen this viral YouTube video of the family cat saving a boy from a vicious dog attack, I have embedded it below. I think this kitty deserves a nice fresh fish for dinner...every day.

An article was posted today in NBCNews featuring the heroics of other house cats.

Here is one of my favorites:

Image of a clawless house cat named Jack that chased a bear up a tree. Image from NBC News: http://www.today.com/pets/good-kitty-these-6-hero-cats-saved-humans-the…

These brave felines must really believe they have 9 lives!!

You can check out the rest of these heroic kitties here.

dr. dolittle Fri, 05/16/2014 - 13:04

Tags

Life Science

attack

behavior

bite

I haven't seen that video until tonight. Most interesting, a cat engaging in tribal protective behavior with a human. Some of the other stories on the linked site are similar in that way.

The consensus explanation for tribal protective behavior by dogs is that dogs are pack animals to begin with, and they see their humans as members of their packs. But I've not heard anything to the effect that cats display pack behavior, and the general impression one gets is that they view us as commensals or something along those lines (mutually independent animals sharing living space). But here we have a few cases where they are displaying self-risking altruistic behavior that's more characteristic of tribalism.

Have any scientists in relevant fields weighed in on this yet?

Also, any explanation of why the neighbor's dog would have behaved as it did, seeking out and attacking the kid in an apparently deliberate manner?

Here in the city we have a phrase for vicious dogs: "weaponized pooches."

Saw a program on PBS a number of years ago about domestic cats. Apparently they will form prides, like lions, even when feral, and mothers are notoriously protective of their young. They can bond well with people, though the social signals are subtle enough that humans miss them. Recently it's been speculated, humorously perhaps, that cats just see humans as big clumsy cats.

Don't know about the dog, but as a breed chows can be very nasty.

Don't know, but that clip is worth seeing. It's wonderful to see the cat - some do become territorial, apparently The dog must be a feral animal, and have a brain problem, i.e. rabid?

Re. Oldbabe @ 2:

Territoriality: interesting explanation for the cats' behavior. Now to find a way to turn these explanations into testable hypotheses. I'm inclined to think that dogs & cats are smart enough to know the difference between a controlled test situation (which they would likely interpret as "playing a game") and a real emergency.

In another article on the linked site, a cat woke up its sleeping human when there was a gas leak in the house that could have caused a fatal explosion: somehow the cat associated the smell of the gas with danger. That strikes me as a different mechanism than territoriality. The photo of the cat that chased a bear up a tree clearly implies territoriality: the bear was not an immediate threat to the cat's humans, but it was certainly a trespasser.

The dog who attacked the kid isn't feral, it lives next door, and the surroundings visible in the video suggest an affluent suburb. Presumably the kid's doctors made sure that appropriate tests were done and precautions taken against rabies. One thing's for sure, that dog's humans are going to get sued until they squeak.

G - Cats aren't pack animals, but they are social animals who care for and will often fight for those they love. Something or someone threatening a loved one on the cat's own territory is particularly outrageous to the cat and most likely to be attacked. The only difference not being a pack animal makes is that a cat is not slavish enough to risk her life for an indifferent owner; you have to give love to get it.

As for the cats who warn of gas leaks and such - they may be simply trying to warn loved ones of danger, or they may have the idea that a human they trust can do something to fix a perceived problem. Our cat (a serious daddy's girl) once woke my husband up in the middle of the night and led him into the kitchen to point out, by staring at it, a large wood roach that was up on the wall out of her reach. Clearly, she had the on-the-spot insight that he could do something about the offending roach if he was made aware of it. After that I told her if the house was ever on fire, she'd darn well better wake us up.

Jane- I'm skeptical of the use of "slavish" as a descriptor for dog behavior, but your item about "threat to loved one on the cat's own territory" is an interesting hypothesis, all the more so because it involves two factors. Thus we should expect to see an increased level of cat response behavior when both factors are involved.

Though, I'm at a loss as to how to operationalize that for testing (which is surprising, as I'm usually pretty good at operationalizing variables for research on humans). Naturalistic observations, "in the wild", are at risk of false negatives: how many threats or trouble-conditions do cats (and dogs) routinely _not_ bring to the attention of their humans, and how would we know?

I'm inclined to think that cats & dogs have very sophisticated ways of understanding the social dynamics in their households, and I would hypothesize that this has largely to do with emotional communication. A cat or dog whose humans are "vigilant" is more likely to be "vigilant," and one whose humans are "nonchalant" is more likely to be "nonchalant," all of this via the cats & dogs modeling or socially assimilating via observation, the emotional states & responses of their humans.

In the bigger picture, this gets at questions of nonhuman intelligence and interspecies communication, both of which are relevant to our attempts to detect and potentially communicate with intelligent civilizations elsewhere in the universe. Approaches to understanding cats, dogs, and other species with which we routinely interact, will be relevant to the day when our space telescopes pick up a signal.

Okay, "slavish" reflects my own preference for cattitude over the behavior of dogs, who are so inherently inclined to fawn over their alphas that even if you are sure they deeply love you, you're not sure they had much choice in the matter. Most dogs will jump through flaming hoops to try to please an indifferent master; treat a cat like furniture and she'll return the favor. Thus I know that my cat's constant solicitations to play chase or to cuddle reflect her voluntary affection for me as an individual. (Also, she doesn't bark at passing strangers or poop on the neighbors' lawns - just sayin'.)

I would be inclined to hypothesize, on the other hand, that dogs are more likely than cats to go to their owners when they perceive a problem because they are so inclined to look to pack leaders for help and decision-making. Cats, even living in colonies, normally hunt as individuals, so their default assumption is likely to be that if they run into a problem, they're on their own. The idea that "someone else could solve this for me" is, I suspect, one that requires much more insight for them.

However, I'm not sure there's a point in formal scientific testing of this kind of thing. We know enormously more about human behavior, and certainly about questions like "what does friendship mean and what kind of behaviors result from it?", from spending our lives observing and interacting with humans than we do from reading scientific publications about white middle-class Anglophone college students tested in totally artificial and therefore "replicable" circumstances. I think the same is true for understanding the behavior of other species. So much more is known now about the capacities of the other great apes because people started observing what they actually do while living free in the wild rather than what they do when they're raised in cages.

I have equal liking for both cats & dogs, and a hypothesis about the independent nature of cats. In the Middle Ages there was a pope who decreed that cats were "the Devil's familiars," and urged the faithful to go forth and slaughter cats, the more painfully "the better to torment Satan." Minus cats, thereby plus rats, thereby plus fleas, thus the Plague. And along the way, natural selection by artificial means: the cats who were more dependent were more likely to have been killed off, and those who were more independent would have been more likely to avoid potentially hostile humans. The independence-minded cats lived to reproduce and tell the tale to their grandkitties.

Yes we should study the behavior of humans and other animals in the naturalistic settings for the respective species. But that by itself isn't sufficient. We also need hypothesis-testing under controlled conditions, otherwise we might fall prey to various anecdotal fallacies. Alternately we should accept that ghosts exist because many people report the experience of seeing ghosts.

This isn't hyperbole. Keyword search author name "Bem" and subject "precognition," and read up. If the critiques of Bem's research are applied to the social sciences as a whole, very little of the social sciences remains. On the other hand, if the standards of the social sciences are applied to Bem's research, it clearly stands. Logical consistency requires applying the same standards to both.

Where I stand on this is, naturalistic and anecdotal research are interesting and informative, but controlled experiments are what count for working from observation to hypothesis to supported theory. The reason we understand friendship among humans in any scientific sense, is that we have first-hand experience of "being human" from which to draw hypotheses for testing. We don't have first-hand experience of "being cats and dogs," so we're missing a major piece of that puzzle. We observe them from the human side of the relationship with them.

I'm not familiar with the literature on animal psychology, so I don't know how good or not-good the methodologies are that are generally used. But it seems like an interesting challenge. And it certainly does have applications, for example in training both dogs and cats (to the extent that cats can be trained;-) to be able to alert their humans to danger, and protect their humans from attackers.

Both types of learning (observation of voluntary behavior, and experiments involving behavior in artificial settings) are useful, but I wouldn't describe either as "insufficient" in general; it depends upon what you want to know. We have generated an awful lot of scientific data and hypotheses from studies of isolated, caged animals that are irrelevant or totally false when applied to free-living social animals. If you observe an animal engaging in a particular behavior, you have adequate reason to say that you know the animal is capable of doing such-and-such.

Indeed, you may not be able to correctly attribute the motivation for that activity. If that's really an important question, controlled studies may be essential or impossible, depending on the details. I consider it reasonable to apply Ockham's razor and believe that my cat purrs when petted and meeps when stepped on because she likes being petted and dislikes being stepped on. If testing this "rigorously" while avoiding "fallacies" would require shoving electrodes into her brain, as some are still doing to laboratory cats, I would consider it immoral to ask the question.

I like your hypothesis about cats' independence, but then you'd expect cats to be less independent in those non-Western regions where they were neither subjected to such horrific persecution nor made a regular part of the human dinner menu. They seem to me to have a similar degree of independence and dignity wherever I go, pathetic overbred house fauna excluded. Someone once commented that cats seemed to come in two distinct personality types, trusting or timid; the latter, if forced into the role of pet, may bond with one person but hide when others are around. It seems plausible that there are two basic survival strategies for a small cat hanging around near humans to eat their vermin (try to make nice in the hope that they will offer protection and shelter, or try to stay out of their grabbing range so they don't kill you just for fun) and the two call for different personality types. Possibly you'd expect cats descended from European cats to be more often genetically inclined to skittishness? Lucky for us, there are still plenty of mellow cats like mine, who thinks everyone's her buddy.

Interesting stuff!

Agreed, observation of behavior is sufficient to say that a behavior is possible, but then at minimum we'd want to have repeated observations to be sure of what we're seeing. One observation isn't enough since mis-interpretation is a known problem in all fields.

Rigorous testing shouldn't require electrodes in brains or other potentially painful means of measurement. Broad-spectrum analysis of vocalizations is one possible route: all that takes is a quiet setting and microphones in the room. Another would be to design sensors that can read any degree of brain activity (as well as heart rate, distribution of temperature in the body, etc.) from a distance, in an environment that's free of electromagnetic noise, and then invite cats & their humans to come in and play.

Here we're up against the issue raised by "skeptics," that human interpretations of other animals' behaviors are the result of anthropomorphizing. As with psi research, the goal should be to meet reasonable criticism but reject the kind of nitpicking that's clearly ideologically-motivated. The ideological motivation re. other animal behavior is the idea that animals are pure mechanism without consciousness or subjective qualia of any meaningful kind. This goes all the way back to the Middle Ages if not before, and is an embedded prejudice that remains to this day.

Excellent point about cat independence & temperament. It would be interesting to compare cat temperament in Europe vs. areas where cats were not subjected to adverse selection pressures from humans. Then comes the question of how much of the cat behavior in each region is a result of genetic selection vs. the cultural variables of humans in these regions.

Your point about "two temperaments" translates to testable hypotheses, and it should be possible to get at them via survey research with well-designed surveys. "For each of the following behaviors, make a mark each time you observe your cat doing this during the next month." The behaviors of "hunt vermin" and "hide" would be mixed into the list.

Anecdotally, two cats who live with a close friend exhibit roughly similar behavior: one of them tends to be social with random humans who drop in, the other tends to hide from random humans until the humans become familiar, and then comes out gradually to interact with them.

Lastly, here's an interesting cat behavior for you:

Years ago a different close friend & his cat (cat A, a black Burmese, which breed is noted for being particularly smart) were living with me. One day Cat A brought home another cat (cat B) who was had an infected cut on one foot and was dirty and likely was abandoned. Cat A made it clear to my friend that Cat B was going to stay. Cat A then proceeded to nurse Cat B back to health and train Cat B in the household norms, and Cat B became a member of the household. My friend was indifferent to Cat B throughout this situation, but Cat A persisted in maintaining his friendship with Cat B. I've never heard of cats picking up unknown strays like this before, much less cleaning their injuries and feeding them etc. until they are healed.

:-) I've seen a few similar stories; in one of them the rescued cat was somewhat mentally inferior to the rescuer and it appeared rather like the cat had a pet cat. I've also read a book by a guy who was devoted to protection of feral cats and rescue of strays, whose female collie loved to help him rescue needy cats and "spoke cat" well enough that many of them socialized with her as freely if she were a cat.

You could definitely try to quantify cats' responses to strange visitors, and see if you got anything like a double-peak graph out of it. Somehow I don't see anyone putting a lot of money and time into it, though.

The Western elite idea that animals are mechanisms (shepherds and dogboys have always known better) dates back at least to the Roman era. It's repeated by a couple of the Roman Stoics, including my usual favorite, Epictetus. (So much for rationality arriving at pure truth.) I speculate that when you live in a society that brutally exploits animals, not just in intensive absentee-owner agriculture and exotic culinary practices but in "circuses" where you are entertained by forcing living creatures to fight to the death, you have a powerful motivation to claim they aren't capable of feeling the tortures being inflicted on them. This nonsense, like Berkeley, can be adequately refuted by stepping on your cat's toe.

I had a cat once chase a fox off my property (we lived in the woods) with exactly the same attitude as the cat who saved the boy. So it might be protective . . . or just territorial.

I have found plenty other stories of cats being heroic. Here is a few: Sammy, Tara, Scarlet, Pudding, Rusty, Pwditat, Faith, Simon, Jessi-Cat, Schnautzie, Tommy, Charley, Leo, Smudge. Those are not the only cats though!

Ghostbusters and tenure in Louisiana

rallain — Sat, 28 Aug 2010 12:46:13 +0000

Ghostbusters and tenure in Louisiana

Ghostbusters is old enough that I don't mind giving away some spoilers. If you haven't seen it, I doubt you are going to.

In the movie, the Ghostbusters capture some ghosts. They keep these ghosts in some "containment grid" device. Someone from the city doesn't like this and comes to turn it off. After much searching, I found the clip.

I am going to talk about Louisiana education and tenure, but first I will look the players in the above scene. What were they thinking? Here is my guess.

Walter Peck: These Ghostbusters are a bunch of frauds. They are just stealing money from people that don't know any better. Ghosts? Really? Ghosts aren't real.

Power Guy: Oh boy, I am in a pickle. I guess I have to do what this Pecker guy says, but it doesn't seem like a very wise thing to do. That chili dog I had for lunch isn't sitting too well in my stomach.

Egon Spenkler: Oh crap. I have worked so hard to set up this containment system and now they are going to shut it off. This is going to suck, big. Oh, I know I took some short cuts and didn't follow all the rules. This system has problems, but it is the best we have.

Peter Venkman: I knew it had to end. This has been one sweet ride. This Ghostbusters gig has been the best way to meet girls. Way better than that silly psychic show I had. I wonder if I could be a politician.

Pre-emptive Ghostbusters comments

Commenter: Um... just so you know...I am a graduate student working on my Ph.D. in Ghostbustersology. You are way off in your portrayal of Peter Venkman. Our research has shown that he is not just looking out for himself. Peter Venkman represents the inner struggle of self over society. Please correct this.

Me: Ok - I am going to fix that.

Now for some Louisiana News:

Here are two news links that describe the situation:

The short scoop is that Louisiana is having budget troubles. One way to adjust to the lower budget would be to eliminate some positions. How do you remove tenured faculty? Oh, just get rid of tenure (essentially). Yes, this is a bad idea. Instead of talking about this, let me give you a Ghostbusters to Louisiana translation (and include what they are thinking)

LA Legislators = Walter Peck: These faculty are frauds. They just sit around in their little offices and they have cushy jobs. They are stealing money from people that don't know any better. This college education stuff is totally over rated.

LA Board of Regents = Power Guy: Oh dear. We don't have enough money to run our universities. We are pretty sure that destroying tenure is a bad idea. That chili dog I had for lunch isn't sitting too well in my stomach.

University Deans = Egon Spenkler: We have worked so hard to build up these colleges. Do you know how long it took to recruit these faculty? We were finally getting some good grants. Oh, I know this tenure system has problems, but it is the best we have. (this could be the faculty saying this too - but I picked Deans.)

I am Peter Venkman: I knew it had to end. This tenure thing was just too good to be true. This tenure stuff was a great way to get blog ideas. I wonder if I can be a space cowboy.

Final note: if you break tenure - think of all the faculty that will be free and running around Louisiana.

rallain Sat, 08/28/2010 - 08:46

Tags

"You've never been out in the real world, Dr. Venkman. They expect results." Dr. Ray Stantz

"I liked the University. They gave us money, they gave us the facilities and we didn't have to produce anything! I've worked in the private sector. They expect results. You've never been out of college. You don't know what it's like out there."

http://www.scifiscripts.com/scripts/Ghostbusters.txt

The private sector just bribes some politicians and steals the money. Billions, not the measley 100 grand a typical acaeemic aspires to. Ask Blackwater or Halliburton. They make Venkman's pre-ghostbusting money-cadging antics look like nothing.

Venkman began his show "World of the Psychic" after the events of GHOSTBUSTERS. Prior to that time, he was an (untenured, clearly) professor at Columbia University. Which was arguably a much better position for meeting girls -- when we first meet him, he's successfully setting up a date with an attractive co-ed by convincing her she has psychic powers.

@ Gabriel Loving the full transcription

Totally awesome way to explain the situation! Love it!

Great! Ghostbusters : Used to be my lovely show!

What a great film...they dont make them like this anymore...any news on the remake?

Yeah, I'm a postdoc right now and have reached the conclusion that staying in the game is a sucker's job. Fortunately, places outside academia are also looking for physicist-hackers... and they can *pay* them and provide a *permanent* position. (Sure, you can get fired, including just because the bosses want to pinch pennies, but that's true in academia as well, and increasingly the difference in permanence is going away.... but the huge pay discrepancy is not. Plus, I have an unknown number of postdoctoral positions still lurk in my future. Hopefully none, but none of them would be permanent and I'd have to be looking for my next gig. So yeah, I don't see the point anymore.

... Peter had the "World of the Psychic" show after Ghostbusters... since it only appears in GB II... just sayin... and Egon's last name is "Spengler" not "Spenkler"... Just sayin... Cause I'm bored...

Good work on this scene breakdown! I like it! +1

Rhett,
Interesting analogy!

We could use another PhD in the group!

You might want to check us out on Facebook and on our website.

Louisianaghostbusters.net

Bustin' for charity is another great way to meet chicks and get your blog ideas out!

appropriate quote from the movie:

Library Administrator: What's has that got to do with it?

Dr. Peter Venkman: Back off, man. I'm a scientist.

Chasing Mummies - evidence and truth

rallain — Sun, 01 Aug 2010 12:09:50 +0000

Chasing Mummies - evidence and truth

Chasing Mummies is kind of like a cross between the reality showness of Deadliest Catch and History's Mysteries. I like these kind of shows. My kids like these shows. It's win-win.

The basic idea of this show is to follow this dude, Zahi Hawass- he is like in charge of all the Egyptian museums. Here is a youtube clip that gives a pretty good overview.

However, I do have a beef - well maybe it is just a small quibble. At the beginning of one show, Zahi is all pumped up about some new discovery. They found some tombs near the great pyramids that seem to be the tombs of workers that did all the construction. Zahi then goes on a small rant (it seemed like a rant to me) to the media and press claiming that THE BUILDERS OF THE PYRAMIDS WERE NOT SLAVES!!!! He seriously looked angry.

Before I go on, let me make something clear. I am not an archeologist - although I have seen Raiders of the Lost Ark like 200 times. So, the stuff I am talking about here is not really whether the builders were slaves or free. I want to talk about science. There are couple of things that Zahi keeps bringing up.

Truth
Prove

Let me go ahead and re-use my favorite Indiana Jones quote:

""If it's truth you are looking for, Dr. Tyree's philosophy class is down the hall"

Science is not about the truth. Science is about building models. So, maybe Zahi is supporting the historical model that it was not slave that built the pyramids. I am ok with that. But is it the truth? I guess we will never know - alas, but that is the way of science. This also goes along with the use of proof (or prove).

There is another small problem. Suppose the previous model of pyramid-buildingology says that it was slaves that built them. There must be some evidence for this, right? And not you get just one piece of evidence that says it might not be slaves, what does that mean? Actually, in this episode, Zahi goes on to show some other evidence regarding the builders - but when he talks to the media, he focuses on just these tombs.

The bonus is when Zahi explodes at one of his research students for suggesting the pyramids were built by aliens. That was golden.

rallain Sun, 08/01/2010 - 08:09

Tags

attack

Science

At the beginning of one show

Zahi is all pumped up about some new discovery. They found some tombs near the great pyramids that seem to be the tombs of workers that did all the construction. Zahi then goes on a small rant (it see

I am not an archeologist - although I have seen Raiders of the Lost Ark like 200 times.

But that was apparently already enough to recognize Hawass for the fraud he is - for you've got him down pat. He might be an archeologist by training, but by function he is a propagandist and politician (he is deputy Minister of Culture). His main interest is encouraging tourism, and he is a best lukewarm, often actively discouraging, of any kind of research that is not likely to result in international headlines.

In any research dispute, he takes the side that depicts Ancient Egypt more attractively to foreign tourists and more acceptable to the Muslim majority in Egypt - for him, there is no doubt the Pyramids were not built by slaves, no doubt the Ancient Egyptian were not supportive of homosexuality etc. etc. - despite the fact that these are all still quite open questions in reality.

As regards the building of the Pyramids, slave labour was the default assumption starting in the 17th/18th century - there was little concrete evidence of it, the assumption was mostly based on the view the Greeks and Romans had of the Egyptian culture, the example of the Mesopotamian cultures and the Biblical accord of slavery in Egypt. Admittedly, there was an element of Western cultural arrogance to it.
More recent research has challenged this assumption, mostly by trying to reconstruct the living conditions in the 'labor' camps, showing that these conditions were better than would be expected for slaves - leading many archeologists nowadays to believe that the Pyramids were built by workers who where paid, perhaps even in some sort of 'stimulus' project.
But the issue is still far from settled, so anybody who claims that there is a definite answer yet is either misinformed or (to be assumed in Hawass' case) consciously misleading.
(On a sidenote, if an answer is ever found, it might turn out a lot more complicated than a yes/no on slavery. In such a hierarchical, theocratic society there might easily have been societal ranks that would be quite difficult to clearly categorize as either 'slave' or 'free man'.)

We have the receipts for the salaries (onions and beer) paid to the workers who built the pyramids. We also have graffiti in which workers identify themselves. They weren't slaves. IIRC, most of the pyramid builders were farmers from the surrounding rural areas, who were otherwise unemployed for substantial parts of the year because of the seasonal nature of Nile agriculture.

Egyptians did practice slavery, but in the form of personal servants, not chattel slavery. Egyptians were a record-keeping people. If there were large numbers of chattel slaves kept in Egypt doing public works projects, there'd be some record of it.

Thanks for this, Rhett. Even as Dr. Jones suggests, some in those philosophy classes may argue that there is no single Truth at all. Anyways, I do feel like there is an actual truth out there and science can be about manipulating it to try to figure it out. I guess I sometimes forget that science is really a step removed from truth and is really a model approximation of reality.

You're right: the truth of this question has to be settled starting in the philosophy class. You have to start by deciding what is or is not a slave. It isn't so easy, because there have been a lot of different kinds of situation called slavery through the course of history.

Personally, I think questions that rely on difficulties of definition of value-laden words are the wrong question. But as we know it's often the sort of question these sorts of programs ask anyway. I've seen Hawass on more serious programs. I can't say I'm over-enamored of his personality, but I can entertain the possibility that he sometimes feels like an evolutionary biologist being asked to produce a missing link.

Real Egyptologists are always very circumspect when discussing Hawass. Look what happened to Joanne Fletcher, for example. He has absolute control over who digs where in Egypt. You need the best butter.

But, from the outside looking in it appears that if you make a significant discovery the cameras don't start rolling until Hawass turns up.

I don't think Hawass is exactly a fraud. I think he is a trained archeologist who has never been terribly good at it, has been an administrator for far too long and nevertheless likes to pretend he can still do it. I've known managers like that.

HP @2. The "recipts for the salaries". I think you are confusing the pyramid builders of the Old Kingdom with the tomb builders of Deir El Medina in the new Kingdom.

Yes, Dr. Hawass is definitely a politician. He is also a showboat, quite competent in his field of Egyptology, and has a positively evil sense of humor. Half the time he goes off on a rant, he is pulling someone's leg. It has been 20 years since I've known him, but ya, that is Zahi, all right.

As ridiculuous as he might be at times, I sure wish the Saudis had someone like him in a similarly empowered position.

Well to be fair, it was white/western scientists who posited the "slave theory" with little to no evidence. And now it's considered the baseline even though as numerous commenters have pointed out there's evidence they were paid, many of them were in-demand skilled laborers, and it might have been part of some sort of government program to keep people employed. Is that guy a patriot who speaks in his country's best interest? Yes. But you'd probably get the same thing if you went almost anywhere. We let China feed us the line about what's going on right now I don't think we should be too angry he's got his own agenda.

Slave labor was an assumption of the West based primarily on the fact that most of the cultures of that time including the Greeks and Romans used slave labor for their projects. Of course the Jews claim credit for building of the Pyramids based on their legends and absolutely no historical or archeological evidence.

It's hard to for Western audiences to get a fair beat on Zahi Hawass because of the enormous animosity that Zionists have towards Arabs in general and Hawass specifically and their orientation towards Israel. Generally though the show is entertaining and informative. I wish more blogs were even-handed in looking at the show as you were Rhett

Chasing Mummies is hysterical. I laugh at Hawass' pharonic statements.

Sure the show is for idiots, Dr H is a total ass, and history channel drops the ball with that show...I would say the show should be called Chasing Dummies - The adventures of Dr Zahi Hawassh*le on History Camel...lol!!!!

Iâm a bit behind in watching the show, but Iâd like to comment on the two episodes I just watched: Bats and Cursed. These episodes were excellent!!! The whiney interns were gone, and we really saw a lot in these programs:
Two beautifully painted 5th Dynasty tombs at Saqqara, Dr. Hawass went under the great Sphinx at Gizeh, and explored caves near the Great Pyramids, attended a wedding in a village, and received an Archadeological Award. (Omar Sharif was in attendance, too!)
Also, Zahi took us to the beautiful tomb of Seti I in the Valley of the Kings, climbed the mountains overlooking the Valley, and viewed a model of the Valley made by famed Egyptologist, Kent Weeks.
Hawass also took us to a Falcon Gallery, and to the Avenue of the Sphinxes in Luxor, where workers are restoring the route that connected the Temples of Luxor and Karnak. Thus far 650 of the 1350 Sphinxes have been found.
This is the reason to watch Chasing Mummies. Sadly I have only one more episode to watch. Hopefully there will be more episodes in the future.
Read this blog for more:
http://lowiczanka.wordpress.com/2010/07/30/beneath-the-surface/

I saw the same show as you Dejah, I enjoyed it a great deal. Thank heavens those interns are gone, my teenagers don't wine as much as the interns do and it takes away from the show. Hawass seemed more himself when he was able to just do what he does best, archeology/egyptology, without having to babysit a bunch of kids with s script to follow. The producers should stop trying to control everything and allow the show to do what I thought it was suppose to, teach us about ancient Egypt. We do not need a stupid soap opera. As far as Hawass's rants, well I would be ranting too if I had to put up with those fellow's, really, those kids are a bit much and would get on anyone's nerves.

Hi,
The show is fake. It's got nothing to do with real archeology/egyptology. Zoe is an actress. Thank god. We wouldn't want her to pie al over ancient monuments for real now, won't we!

More Dangerous Kids

rallain — Sun, 11 Jul 2010 14:28:09 +0000

More Dangerous Kids

My car had a flat tire. When you get a flat tire, you might as well make something useful of it - right? As I was jacking the car up, I had a great idea. Use this for one of my "Spoof Science" videos. The only problem is that this takes a ton of work to put together a short video. So, I am just going to talk about what I could have done.

Here is a quick clip of my 4 year old lifting the car.

So, he lifted the car - it maybe be difficult to tell, but he did. HE LIFTED THE CAR! Ok, I know, he only lifted part of the car. If I were to use this in a real Spoof Science video, I would have something to more clearly show that the car actually moved up.

I am going to estimate that he lifted 15% of the weight of the car. (I just made that up - it was the back end and just 1 tire off the ground). The mass of the Mazda 5 is about 1600 kg. This gives a total weight lifted of:

Note: at this point in the video, I would completely ignore the fact that he only lifted the car less than a centimeter. Really, data like this just isn't important when you are trying to show something cool. Now, I can extrapolate this incredible result. If this kid can lift over 2000 Newtons, what will it be like when he is full grown? How much of his body mass can he lift? If the kid has a weight of about 160 Newtons, then he is lifting about 14 times his own weight.

What if I could lift 14 times my own weight? I would be able to lift 9800 Newtons (or over 2000 pounds). Ok, so you see how I would do this, if I were to do it.

What about the real physics? If you think about it, it is still really cool. Even though he only lifts it a small amount, he still lifts it. How does this work? This works the same way all simple machines work - by work (the physics work). Recall that work done bya force is:

Where Δr is the amount the force moved the object and θ is the angle between the force and the displacement. The key is that the work done by the kid is the same as the change in energy of the car (well, car plus Earth system). The car increases in gravitational energy by an amount:

I hope it is obvious the m_cg is the weight of the car (or a portion of the car). Relating this to the work done by the kid:

If I estimate that the car moved up 0.005 meters and the kid pushed down 0.3 meters, then he had to push with a force of 40 Newtons (or about 9 pounds). Pretty cool, if you think about it.

rallain Sun, 07/11/2010 - 10:28

Tags

sure, i suppose the physics you presented is accurate.

however, there is another competing theory that i would like to address:

what you actually did was breed a giant ant then dressed it in a costume of your child. the ant then actually *did* lift 14 times it's own body weight. which really means it is a wimpy giant ant, cuz they r supposed to be able to lift hundreds of times their own weight.

@Rob,

Wow. You figured it out. I was trying to be all deceptive, but you saw right through it. Kudos to you.

Eeek! Giant insects! I banish thee with the Square-cube law!

(Although that might explain why said giant-ant-in-guise-of-a-child appears to be so weak.)

Great stuff. Takes me back to when I used to manage a flower shop. The people we hired to do the arranging were very artistic, and not just anyone can create a good arrangement. I like the third one the best, with the little gold bird, and blue surrounding yellow.

ScienceBlogs: What if...

rallain — Fri, 09 Jul 2010 06:33:40 +0000

ScienceBlogs: What if...

In regards to the recent PepsiCo blog situation (you know the one I mean), I wasn't going to say much. First, because Chad did a good job at expressing my views (without me even telling him ). Second, I am just happy to be at ScienceBlogs - I had been kicked off two servers and had to hitch a ride on a friend's server (thanks Bill) before arriving here.

Some other bloggers, were a little more put out. Now I understand why. I came to this understanding by doing a thought experiment. What if it wasn't PepsiCo that paid for a sponsored blog? What if instead it was ESPN's Sport Science? I think I would consider leaving too (but it would just be an idle threat).

rallain Fri, 07/09/2010 - 02:33

Tags

I can't wait for the flood of useful blog posts about the angular power of the vector ski mass!

Spoof Science: Are kids dangerous?

rallain — Fri, 04 Jun 2010 12:34:32 +0000

Spoof Science: Are kids dangerous?

I got tired of attacking ESPN Sport Science. Well, tired of attacking might not be the best term. How about, attack in a new way (here are my older Sport Science attacks).

Check out episode 1 of Spoof Science:

A couple of notes:

Watch it youtube if you want the HD version
Making videos takes WAY longer than a blog post
If you hate hearing your own voice, you will really hate hearing your own voice AND seeing yourself while you are editing

rallain Fri, 06/04/2010 - 08:34

Tags

Kind of "Deadliest Warrior" ( http://www.spike.com/show/31082 ), but more useful and watchable.

wonderful!

"If you hate hearing your own voice, you will really hate hearing your own voice AND seeing yourself while you are editing" - Very good!

But, how about a(my) sister reading out your(my) "random thoughts" from your(my) website, in the style of a serious TV news reader? Huh, beat that one.

Paper shuffle, paper shuffle...

MR dot physics,

look at this

http://www.eepybird.com/featured-video/the-coke-zero-mentos-rocket-car-…

"All that power is pushing against a wall braced with 3,600 pounds of cement blocks. So all the force is directed into moving the Coke Zero & Mentos Rocket Car forward."

That doesnt sound right, a bit wrong eh?

Can you confirm

Absolutely priceless.

Really enjoying your posts! This is going to get some air time in my physics class tomorrow.

Ye we should make a border for the things which are publishing through common medias ,medias have important role on making personality.

1:25-1:38 Totally precious outtake

Electric eel at the aquarium

rallain — Mon, 31 May 2010 12:23:45 +0000

Electric eel at the aquarium

We went to the aquarium, the kids like it. In the Amazon river section, they have an electric eel. Here is the sign next to the Eel.

Sorry for the poor image quality. I took the picture with my crappy phone and didn't even realize it was bad until later. I used some magic on it to make parts of it readable, but if that was not good enough, here is what it says:

The Electric Eel is the most powerful of all the electric fishes. It can discharge up to 650 volts: six times the power of a household current. A shock can fend off attackers or stun prey so the eel doesn't risk getting hurt in a struggle.

A person might survive one blast from an Electric Eel, but not several.

Let me address this in three ways. First, what is wrong with this. Second, why is this a problem that it is wrong. Third, what would I have put on this board.

What is wrong with this?

The biggest problem seems to be the confusion between electric potential (measured in volts), power (measured in watts) and current (measured in amps). The narrative clearly says that the 650 VOLTS is six times the POWER of household CURRENT. Those are three different things.

If you look at the Wikipedia page on electric eels, it says the eel could produce 500 volts at 1 amp of current. For electric circuits, the following is the relationship between electric potential, electric current and power:

This would make the eel capable of 500 watts in the attack.

What about a household circuit? First, these are alternating currents (AC), but let's just pretend it is DC for simplicity. A normal household outlet is at 120 Volts and can produce currents of about 10 amps. This would be a maximum power of 1,200 watts. So, the eel is not 6 times the power of the household outlet.

Note: I would not recommend sticking your finger in either an electric eel nor in a household outlet.

Why does this bother me?

Really, this is a similar problem to the problem with ESPN Sport Science. Here is a great opportunity to help people learn something, or at the very least do no harm. Also, clearly there was some effort put into this production. I bet the sign alone cost at least $100. Yet it appears that no one bothered to contact a local high school physics teacher to look over this. If you can't find someone, email me. I will be happy to look over your sign.

I could see if a blogger made this and it was wrong. Mistakes happen, it is no big deal - especially when it is just one person. But this case is different. How long will that sign be there?

My sign

Ok Mr. big shot blogger man. What would you put? Well, first I would state the important details.

An electric eel has multiple cells along its body that create a change in potential of over 500 volts. The typical current produced in an electric eel attack is around 1 amp.

Now, the problem is that most people of no experience with with 500 volts is like or 1 amp is like. So, I could add something like this:

500 volts would be the same potential as about 330 D-cell batteries connected together. A typical two-battery flashlight might use a current of about 1 amp. However, since the eel has a much larger potential difference, the effects can be severe.

Just my first thought. You could probably come up with a cool graphic to show a comparison between the eel and a flashlight. Oh - how about two electrodes that visitors can touch and get shocked. Next to it, there could be a sign that says "that hurt, didn't it?"

rallain Mon, 05/31/2010 - 08:23

Tags

Your sign would never be accepted; not pithy enough. In exhibits directed at children and laymen, you need examples that people are familiar with.

While the comparison to 330 D cell batteries is a good start, a better analogy would be compare the power produced by the eel to that required to run an appliance. A small microwave oven would be my choice.

You could also say that, if the eel kept at it, you could make half a glass of water (4 oz or 118 ml) go from room temperature (22C)to boiling in about a minute and a half. Of course, I don't think that eels put out that much total energy.

Voltage labels are usually given in RMS values.

You still miss the time dimension. The output is pulsed. A 20 kg fish can't produce half a kilowatt continuously for a long time.

>change in potential

Too hard for me. (I aced the first semester of physics - mostly mechanics. I barely passed the second semester, because I got totally stuck on how weird electricity was.)

The Wikipedia text looks good, but some simple comparison would be nice. How does it compare to an electric fence?

Cripes. Your details aren't really helpful for the intended audience, and your comparisons stink. How does one visualize 330 D Cell batteries? And who the hell uses D cell batteries these days? I mean, I've got a knock-off mp3 player that takes one AAA battery. Otherwise, all my gadgets (laptops, etc.) come with built-in lithium batteries. And a 1-Amp flashlight? That would be a honking big LED flashlight.

Obviously I'm being overly picky, but that's because I agree with you that the original sign stinks and is a missed opportunity.

My comparison would be something like "can generate enough electricity during an attack to power five conventional 100 W bulbs, but for a a quarter of a second". Or more gruesome: "four eels attacking together are about as powerful as an early model electric chair, though only for a half a second (or whatever)". If you like the numbers, preface it by just the facts: "An eel can produce about 500 Watts of electricity."

-kevin

>> I bet the sign alone cost at least $100. Yet it appears that no one bothered to contact a local high school physics teacher to look over this.

That pales compared to what I'm sure they pay you to teach physics, and you can't be bothered to have a high school physics teacher look over your blogs.

Yes, I think this is a tough one. What kind of comparison would you like to make in a short space? What concepts do you want to try to support? I am not sure what the answer is.

I'm sorry, but if that is a response to my post I honestly can't follow it.

>> What kind of comparison would you like to make in a short space?

I was comparing the $100 you presumed they spent on the sign against your salary.

>>What concepts do you want to try to support?

I'd like to support the idea that a physics instructor should be open-minded, be willing to admit when he might be wrong, and not call people hoaxers on his public forum if he doesn't want to become the poster boy on thier forum.

>>I am not sure what the answer is.

To which question - DDWFTTW?

How long will that sign be there? How long has it been there? I took my nieces to this same aquarium almost 20 years ago and I have a distant memory of reading this very same sign (or a sign very similar).

I suspect that neither the museum nor the sign maker were trying to make any point other than that we should be impressed by the interesting electrical fish killing power (not IV) of the electric eel.

By the way, I went to the WWII museum on Saturday. On the front page of a paper posted on a wall (I forget from where) describing the D-Day invasion were two other lead stories. The first described how a 26 year old single woman was murdered blocks from her home and the second described how a 14 year old formerly fat girl had starved herself to death because she was tired of being ridiculed for being fat. What does this have to do with physics? Nothing I'm happy to say.

i had the same thoughts as Rhett after i read the sign. then i realized he was going to point out the issues with power, electric potential and current. it would be nice if the aquarium found out about this post and fixed up the sign.

@spork:feeling grumpy eh?

>> feeling grumpy eh?

Yeah - I suppose it annoys me when an incompetent "physics instructor" accuses me of perpetrating a scam on his public forum just because he can't understand high school physics (and doesn't care to try).

is a eltric eel make power?

do eletric eels have tounges

MythBusters' energy explanation

rallain — Thu, 06 May 2010 16:32:57 +0000

MythBusters' energy explanation

I already mentioned the MythBusters' crashing two cars episode where they correctly doubled the speed of a pendulum type object. Overall, this was a very visual (although expensive) demo. There was one part that left a sour taste in my mouth - the final explanation from the narrator. First, they showed this.

And then they had an explanation that went something very similar to to this (after restating what the sign above said)

"Although the two-car crash doubles the speed, the energy the crash is transferred to twice the mass resulting in a crash that looks like just one car hitting a wall at 50 mph."

Here is the graphic that went with that.

I had to re-listen to this narration a couple of times because something seemed not quite right. First, let me comment on the last diagram. Really, maybe it would have been better to leave this off. It doesn't really add any useful explanation other than to point out that the kinetic energy is dependent on the square of the velocity. And what about the narrative? I think what bothered me is that they said the two-car crash doubles the speed, but what they probably should have said is "the two car crash doubles the kinetic energy and this energy is spread out over 2 cars." Using their statement, you would say "oh, double speed means 4 times as much energy."

Here is the real question: what concept are you trying to get across? Newton's third law? The idea of kinetic energy? Conservation of momentum? I would just pick one and stick with it. Otherwise, you are kinda implying that "action and reaction" have something to do with kinetic energy. Oh, have I ever mentioned how much I hate "action and reaction" explanation of Newton's 3rd law? Action? Reaction? How about this for Newton's third law:

Forces are an interaction between two objects. Forces come in pairs. Or, if you must: For every force there is an equal and opposite force.

Oh sure - you can make the action reaction thing work, but it can also cause problems. Either way, I would suggest sticking with the energy explanation. Here, I want to help. I am going to give an energy explanation that the MythBusters could use and a force explanation for the two-car collision.

Two-car crash, energy explanation

Why are two cars crashing into each other not the same as one car going into a wall at twice the speed?

Explanation: In terms of energy, the energy of motion is called kinetic energy. Kinetic energy depends on the square of the velocity. This means a car moving at twice the speed with have 4 times the kinetic energy.

So 10 + 10 is not the same as 40.

Two-car crash, force explanation

This is a little more complex, but I will try to make it simple. First, two key points:

Forces are an interaction between two objects. Object 1 pushes on object 2 the same as object 2 pushes on object 1 (same interaction).
A force on an object changes the object's momentum where momentum is mass times velocity.

Suppose a car crashes into a wall with a velocity v. While it is interacting with the wall, the wall exerts a force (F) on the car and the car exert a force F on the wall.

Where the force the wall exerts on the car and the car on the wall have the same magnitude. Now, what if I replace the wall with another identical car traveling at the same speed?

Since the initial momentums are the same and the forces are same, the effects are the same on the two cars. So, two cars are the same as one car into a wall. If I now double the speed, I will have different initial momentum, so it will not be the same.

Other stuff

I actually forgot that I have talked about the MythBusters colliding two cars before. I wrote this post the first time they did this myth. That is a little more detail than I have here. Also, a similar thing came up when the MythBusters tried to pull two phone books apart. Here is my discussion of forces in that situation.

One more thing. I would like to emphasize how awesome this demonstration was. You hear people discussing things just like this all the time, but no one actually does it. For many physicists, the actual experiment doesn't mean much. However, to many people this experiment is important. They just need to fix their final explanation (call me next time and I will be glad to help).

rallain Thu, 05/06/2010 - 12:32

Tags

I can't wrap my brain around how Newton's 3rd law logically proves Jamie's hypothesis wrong.

Doubling the mass (action) results in what type of reaction? (Sorry for using those terms.)

@C. Felix,

I am not sure I proved he was wrong, maybe instead I just showed that two cars colliding is the same as 1 into a wall at the same speed. If that works, then I guess it follows that double the speed would not be the same.

I started to think about this in terms of reference frames and this really makes me believe that energy is the wrong way to explain this problem to the average person.

If you look at the proper reference frame of the orange car, because the event is happening to it. The person in the car would see a yellow car with E=40 hitting them or a wall with E=40 hitting them.

Am I thinking about the reference frame incorrectly?

Got this idea from Al Guenther: to teach newton's third, cut a plastic pear in half and put a force vector in each half. HA! Forces come in pears. Thought you might like that if you hadn't seen it before.

@Matt,

Great idea. How about this modification. Make a plastic arrow for a vector. Take a real pear and embed this plastic arrow inside. Then when you cut it open in class you can say vectors come in pears.

Ummm... Isn't the velocity in the kinetic energy equation suppose to the relative velocity between two objects, not relative to a fixed point in space or the point of the collision. Isn't the relative velocity between two cars traveling at 50 mph the same as one car travelling toward a wall at 100 mph.

Me thinks a few mistakes were made.

@Evan,

Kinetic energy is not independent of reference frame. If you move to the reference frame of one of the cars, you would see a different total KE before the collision. What you would agree on is the changes in energy during the collision.

My statement was that the v in kinetic energy equation is based on relative velocity. Relative velocity is just that, Relative. Using the earth as a universal reference is a very common mistake. Each object's kinetic energy relative to the earth is irrelevant. We only care about the kinetic energy relative to the objects in the experiment. We're forced to choose one of the objects as a frame of reference. With the wall the choice is obvious. We have to use the wall as a frame of reference. With two cars travelling towards each other we have to pick one of the cars as our frame of reference and consider that car stationary. Thus, the relative velocity is the same between the two experiments. If the mass of each car is the same and the relative velocity is the same, then the kinetic energy is the same. It's like saying 1/2m(100)^2 = 1/2m(100)^2.

Basically, I'm saying your explanation using kinetic energy is wrong because you calculated kinetic energy relative to the earth and not relative the objects in the experiment.

I'm also saying that a car hitting the wall at 100 mph hit that wall with the same kinetic energy as two cars hitting head on at 50 mph. Maybe not relative to the earth, but relative to one of the cars.

Because kinetic energy is dependent on frame of reference, it's absolutely critical that you choose a valid frame of reference.

But nobody has addressed deformation, which Adam and Jamie used *as their measurement* of impact (along with G-forces i.e. deceleration). Of course the clay between the weights on two moving hammers squished only as much as the clay in one hammer did... there was twice as much total clay to absorb the impact. Likewise, when one moving car hits the wall, the wall shows no deformation - only the car is squished. When two cars hit with the same relative velocity as in car vs wall, *both* cars get deformed - so each individual car deforms less.

@Pteryxx

I agree 100%. The difference in damage had more to do with elasticity then it did with force. Elasticity was not constant as the wall was far more elastic then the cars. The amount of force due to relative kinetic energy was the same for the 2 cars traveling at 50 and the one car traveling at 100. The difference was the one car traveling at 100 was the only object in the collision that could absorb energy through deformation. Thus it was damaged far more. The energy had to go somewhere.

I agree with Rhett that the action-is-minus-reaction is a particularly awkward way to formulate that law of motion.

Whatever Newton's reasons were to formulate the third law in that form, a far superior form is present in the Principia. In the Principia, the three laws are followed by corrollaries, and the fourth corrolary states the third law in dynamical form:

"The common center of mass of two or more objects does not alter its state of motion or rest by the actions of the bodies among themselves."

In retrospect we would have been in a far better situation if Newton would have asserted the third law in that dynamical form. (In fact many textbooks do present that dynamical form as the third law.)

I can't resist fantasizing what things would be like if that dynamical form would be the canonical form. Then that whacky "action-is-minus-reaction" thing would not be there to confuse the guys who write the Mythbuster narrator's script.

Going back once more to the dynamical form:
"The common center of mass of two or more objects does not alter its state of motion or rest by the actions of the bodies among themselves."

This form emphasizes the mutualness, and it is uncommitted as to what force is. It's a statement about motion, not a statement about force. For better education that "action-is-minus-reaction" thing ought to be phased out, and replaced with the dynamical form.

You write: "The two-car crash doubles the kinetic energy and this energy is spread out over 2 cars." I think this is the clearest explanation for why 2 cars hitting each other @ 50 mph might do the same amount of damage (to Car #1) as would Car #1 hitting a stationary wall @ 50 mph.

For me, the tricky part is convincing myself why, in the wall case, we don't need to worry about some of that initial KE getting transferred to the wall instead of going into damaging Car #1. One model that seems to work is if you think of the wall as a spring with spring constant k >> F_max/L, where F_max is the max force w/ which the car pushes back while being crushed, and where L is a characteristic length scale in the process of crushing the car (F_max*L ~ energy that goes into damaging Car #1 during crash).

Then, in the two-car collision, where each car has initial speed v, all the initial KE is shared equally between Car #1 and Car #2 during the crash:

2 * 1/2 m v^2 = 2 * (Energy that goes into damaging Car #1),

=> Energy that goes into damaging Car #1 = 1/2 m v^2.

But in the Car#1-hitting-wall collision, where Car #1 again has initial speed v, the initial KE is shared unequally between Car #1 and wall during the crash:

1/2 m v^2 = E_wall + (Energy that goes into damaging Car #1)

Now, IF the wall acts like an ideal spring w/ k >> F_max/L, and if we can assume the wall/spring ends up compressed by a (tiny) distance x, which is how far it had to compress to push back on the car with the required crushing force F_max, we have

E_wall = 1/2 k x^2
= 1/2 k (F_max/k)^2
= F_max^2 / (2k)
= F_max*L / (2 kappa)
= O(1/kappa)

where kappa = kL/F_max >> 1 is the dimensionless large parameter in our approximation. And recall that, by definition,

Energy that goes into damaging Car#1 ~ F_max*L
= O(1);

that is, in the limit kappa->infinity, E_wall is negligible in comparison with the energy that goes into damaging Car #1. Going back to our energy-transfer eqn for car-hitting-wall, and taking the 1st term on the RHS to zero, we thus have

Energy that goes into damaging Car #1 ~= 1/2 m v^2,

which is the same amount of energy that went into damaging Car #1 in the two-car collision when *both* cars had initial speed v.

But is it accurate to treat the wall like a large-k spring in this manner? I don't know!

Re the comments about reference frames: Remember that the COM reference frames of the cars are NONinertial. (As the cars get crushed, they decelerate.) So the physics can't be expected to work properly in those frames. From his own COM frame, Car #1 thinks there's twice as much energy to go around than there actually is (1/2 m*(2v)^2 = 2 mv^2 instead of 2* 1/2 mv^2 = mv^2), and he'll therefore be confused about why there isn't more damage to the two vehicles.

@Carol,

I am not ignoring your comments, I am just taking time to think of a response. Sorry for the delay.

1. One almost always has to make simplifying assumptions when "modeling".

2. One must "model" in order to keep the math reasonable.

3. Sometimes the real world answer is lost in the over simplifications of the models.

4. In this case, I think the key is to ignore the crumple factor, focus on the choosing the inertial reference frame for each case and let the kinetic energy tell the tale.

They should have made a wall traveling at 50mph and a car traveling at 50mph hit each other.

The energy argument is wrong, by the way. The momentum one is correct. The problem with the energy argument is that you have all assumed that there is such a thing as "absolute kinetic energy". Unfortunatley, that does not exist. Only changes in energy are meaningful - this is 1st year physics. I'll give you an example. Say you are in a train moving at speed v (not accelerating) and the windows are blacked out. You would say that you have zero kinetic energy. Now, and observer on the ground says that you have 1/2 m v^2 kinetic energy. Who is right? It's meaningless since the notion of absolute KE is just as meaningless as absolute potential energy (PE). If you considered changes in energy, then things would be more meaningful.

Finally, this is an in-elastic collision, so what you can apply is conservation of momentum. Mechanical energy is not conserved in this collision.

Summary: Newton's third law, and the cons. of momentum explain this result. That is all you need. This whole issue of different frames of reference (cars frame, ground frame) is a red herring.

I have a queston if there were to eople in the wouds how would last longer the skiny one or the fat one ??????

18,000 lbs of cumulative force

rallain — Wed, 21 Apr 2010 20:44:24 +0000

18,000 lbs of cumulative force

I want to give ESPN's Sport Science another chance. The segment on Tim Tebow didn't really have any errors. I thought, cool - what about this one on Jason Pierre-Paul? Here is the clip. Oh wait, embedding is disabled. Ok - if you want to watch go here (the image is a link)

The goal of this segment was to examine why Jason is so awesome at tackling. The answer: because he can do flips. Really, that was the answer. Let me briefly go over some of the problems with this segment.

Correlation does not mean causation

They didn't say it explicitly, but it seems the are saying the reason he can tackle so well is because he can do "back flips". NOTE: those are back handsprings, typically (according to my daughter) if you say back flip, you probably mean a back-tuck and your hands don't touch the ground. This is a back flip:

Anyway, Sport Science has already shown that they don't understand correlation. So, the last thing to say - xkcd has the best response to "correlation implies causation".

Other claims

While doing the back handsprings, Sport Science says the following:

Jason rotates around his center of mass at 11 mph
Feet and hands sustain forces up to 3 times his body weight - (over 800 lbs)
He can do this 23 times in a row - that is cyclic loading (whatever that means) of 18,000 lbs of cumulative force (in less than half a minute)
His body absorbs more weight than the entire roster of the New Orleans Saints (Go Saints)

So, which of these claims are ok and which are crazy? The 11 mph seems like it would be easy to verify - even though the problem is not really defined. I guess they meant that his feet are moving 11 mph? They should have instead talked about his angular speed. Also, I could do the force exerted on the body during the "spring" part of the handspring. It could easily be over 800 lbs. But you know what I am going to talk about, don't you?

Why do they make this stuff up? Oh, if you push with 800 lbs for 23 times - that is THE SAME AS LIFTING ALL THE NEW ORLEANS SAINTS! I know, they didn't say he could lift the Saints, but it kind of implies that - doesn't it? Let me first point out that Sport Science first claimed that Jason pushed with 800 lbs both with his feet and hands. If he does 23 hand springs, (by their methods) that would be 23*2*800 = over 36,000 lbs.

Next, a thought demo. Let me assume that all the Saints have a weight of 18,000 lbs. Let me also assume that when I run, my foot hits the ground with a maximum force of 1.5 times my body weight (really, this is a silly thing to say since it is not just the peak force - but I will use their silly method). Also, suppose that with each step, I move 4 feet. So, how many steps would I have to take to have a "cumulative force" equal to the weight of all the Saints? Just 75 steps or running just 300 feet. I can do that.

Seriously, what does this have to do with tackling? Sport Science - you should stick to reproducing Kobe Bryant's fake jump over a car. You did a pretty good job at that.

rallain Wed, 04/21/2010 - 16:44

Tags

Re: "His body absorbs more weight than the entire roster of the New Orleans Saints"

I didn't watch the show, but I love the "scientificy" expression "absorbs more weight than..."! It makes Jason Pierre-Paul sound like he's starring in an advertisement for paper towels.

Physics Tips for Media

rallain — Mon, 19 Apr 2010 12:50:28 +0000

Physics Tips for Media

You probably already know how I feel about the "media" and their physics explanations (see attacks). Let me summarize the problem. There are a whole bunch of cool shows on tv that deal with sciency stuff - that is good. These shows then try to teach some science along with their demos and explosions and stuff. This is also good. However, they usually butcher the explanation part. Some of them (ESPN's Sport Science) must just literally make stuff up that sounds cool.

I understand that in common usage, things like "force" can be used lots of different ways. I am ok with that. Also, sometimes a person on a show will use a term incorrectly (MythBusters do this all the time). This isn't so bad if it is not an "official" explanation. If there are special graphics and a narrator, the explanation should at least not be wrong.

I want to help. Here are some commonly used "physics" terms and definitions that don't suck.

Force

Definition: A force is an interaction between two objects - usually describe as a push or a pull.

Other stuff: Forces are measured in units of Newtons or Pounds. If there is only one force on an object, it will change the object's speed and or direction. Force is a vector -this means direction means something.

Wrong: It seems the most common error is to associate a force with one object. "That ball had a lot of force" or "that ball had a lot of force behind it". This maybe confusing force with momentum (which is different).

Momentum

Definition: Momentum is a measure of how much "oomph" a moving object has. This IS a property of the object. Mathematically, momentum is the product of mass and velocity (if you are not moving near the speed of light).

Other stuff: Momentum is typically used when people are talking about collisions - and that is ok. Also, it is common to say that momentum is transferred from one object to another in a collision. I guess this is ok - but really it is that the total momentum vector for a closed system remains constant.

Wrong: I can't think of a wrong use of momentum off the top of my head. Probably the biggest wrong use is to not use momentum but to use the term "force" instead.

Energy

Definition: It might be surprising to you, but I think energy is not so simple to define. Most texts say energy is the ability to do work - I don't really like that one. For this use - I guess it would be easiest to say that there are two types of energy - particle energy and field energy (I know that is not a definition). Maybe I should just say that using "energy" is a way of looking at interactions.

Other stuff: Energy is not a vector - direction does not matter. I would consider it a property of an object. Here are some examples of different types of energy that come up:

kinetic energy
gravitational potential
electric potential
thermal energy
light energy

Collisions

I don't have a definition for collisions, but it comes up a lot on shows. What happens? Well, let me say what doesn't happen. If an object is crashing into a wall, it does not transfer its kinetic energy to the wall. It is common also to talk about how energy is dispersed in a collision. Maybe this isn't really wrong - but it isn't the best thing to talk about. There are two important things. First, the momentum principle (more details on the momentum principle). It says for a given object:

Basically, the total force on an object changes its momentum. For a given change in momentum (like an object stopping) you can use a smaller force if the time of impact is larger. If there are two objects (and no external forces) then the total change in momentum of the whole thing is zero vector.

What about damage? Damage to a human is probably best done by looking at the acceleration (but even that is sometimes tricky). The MythBusters use this a lot - and usually correct. The problem is that if you have two different mass people falling from the same height, they will have different momentums and different forces but similar accelerations.

rallain Mon, 04/19/2010 - 08:50

Tags

I think the issue of force is a bit more subtle than that. While it's true that forces come in pairs and are caused by the interaction of two objects, it is perfectly accurate and correct to speak of the force or forces on an object. When you talk about the net force on an object, it's impossible to refer to the "other" object involved.

At the level of mechanics as shown in these types of science programs, I think it's fair to say that a force is something imposed on an object causing it to change direction or speed; it is not a property of an object, but something external to it.

As a high school teacher, I find it really difficult to define energy - I will now check the post you link to.
One definition I use is that energy is like the "currency" of the natural world. You need to exchange some for anything to happen, and you can find it in different "denominations", but it is all equivalent.
Of course, there is no machine that prints "money" in the physical world...

When I was at school in the middle of the last century energy was defined as the capacity to do work. Yes, vague I know. But we went straight on to work is done when a force moves its point of application a certain distance. Then the energy of a system in one state relative to another state is the work done to change from the initial state to the final state. From this expressions for kinetic and potential energy drop out immediately and it's easy to show that the potential energy in raising an object to great height is equal to the kinetic energy when it crashes to earth.

By concentrating all the time on the work done when an energy transfer takes place, the idea of energy as the capacity to do work was no longer vague and when we got to thermodynamics and the concept of energy that wasn't available to do work (even though it had the capacity) didn't seem contradictory.

How about this pet peeve of mine:
Using "rate of speed" in place of just "speed" (or worse, in place of "velocity"). I think people use it to sound smart, and instead it just makes them look stupid.

I like Feynman's definition of energy: We don't know what energy actually is; it's an abstract thing, but we know that we can calculate this number, thing, or 'energy', and it would have the same value no matter what happens (in a closed system).

I despise the energy definition "capacity to do work". One then has too look up what "work" means. Much like a dictionary that gives you a definition that forces you to look up to other definitions.

@V. infernals,

that is a good one - forgot about that. I think ZapperZ had a good rant on that - yes: http://physicsandphysicists.blogspot.com/2010/02/more-rate-of-speed.html

@brimn,

Yes - that is a good definition of energy. Leave to Feynman to give a good explanation.

I always wonder when a moving object is being discussed someone might say, "its momentum carried it forward" Would it be more correct to say its inertia? (or less correct?). Is that possibly a way that momentum is misused in media?

@Eric,

Surely momentum is misused in the media - but I am not sure about "momentum carried it forward". Clearly, it is not the best thing to say - but I don't know if it is exactly wrong. I guess it is saying that there is some force on it. This force changes the momentum. Well, I guess the assumption of a force is wrong.