speed
dr. dolittle | September 3, 2015A new study published in the Proceedings of the Royal Society B: Biological Sciences provides evidence that hummingbird tongues act like micropumps when drinking nectar. This finding is in contrast to the long-held belief that their tongues use capillary action to pull in fluids. A team of researchers from the University of Connecticut used high-speed film to capture 18 species of wild hummingbirds as they drank from special transparent feeders. They made sure to mimic wildflowers by developing feeders with similar shapes, volumes and concentrations of nectar as the real thing. What they…
dr. dolittle | April 11, 2014
Gray's paradox was originated by the zoologist James Gray in 1936 (J. Exp. Biol. 13: 192–199, 1936). The paradox questioned how a dolphin is able to swim fast (~10.1 meters per second according to his calculations) with what he saw as a limited ability to generate that much power. Therefore, he concluded that dolphins must have some mechanism or adaptation to reduce drag (Davidson College).
More recently, Dr. Frank Fish (West Chester University, Pennsylvania) was quoted in The Scientist saying, “To resolve the paradox was to assume that flow over the dolphin’s body is laminar, meaning that…
esiegel | December 11, 2013"Where you used to be, there is a hole in the world, which I find myself constantly walking around in the daytime, and falling in at night. I miss you like hell." -Edna St. Vincent Millay
It was just a little while ago that we were all speculating wildly -- and optimistically -- about Comet ISON, as it plunged towards the Sun from its origins in the very, very distant Solar System. As its perihelion date (the moment of closest approach to the Sun) drew near, you may have noticed something interesting about photos of the comet: it's tail appeared to get longer and longer!
Image credit &…
esiegel | May 10, 2013"As seismologists gained more experience from earthquake records, it became obvious that the problem could not be reduced to a single peak acceleration. In fact, a full frequency of vibrations occurs." -Charles Francis Richter
You've all been around long enough to be familiar with the severe damage that earthquakes can cause, rattling and cracking the ground, shaking down buildings, and creating catastrophic tsunamis tidal waves. In short, the largest ones that occur in the wrong places will cause billions of dollars worth of damage and will kill thousands of people.
Image credit: AP / Press…
esiegel | April 26, 2013"All our sweetest hours fly the fastest." -Virgil
If you've been around the block once or twice, you know that the speed of light in a vacuum -- 299,792,458 meters-per-second -- is the absolute maximum speed that any form of energy in the Universe can travel at. In shorthand, this speed is known as c to physicists.
Image credit: user Fx-1988 of deviantART.
But you or I, no matter how hard we try, will never attain that speed. There's a simple reason for this: we have mass. And for an object with mass, you can accelerate it all you want, but it would take an infinite amount of energy to…
drorzel | August 12, 2011I am an inveterate driver of "back ways" to places. My preferred route to campus involves driving through a whole bunch of residential streets, rather than taking the "main" road leading from our neighborhood to campus. I do this because there are four traffic lights on the main-road route, and they're not well timed, so it's a rare day when I don't get stuck at one or more of them. My preferred route has a lot of stop signs, but very little traffic, so they're quick stops, and I spend more time in motion, which makes me feel like I'm getting there faster.
That's the psychological reason, but…
rallain | July 30, 2010The Lord of the Rings trilogy came on TV again recently. My wife and I can't help but to watch this even though we have it on DVD. Anyway, I was thinking about the part where Gondor sends a signal to Rohan asking them for military aid. Since this was before the invention of email, they had to do it with a signal fire. Hopefully this clip won't be a spoiler for you, but this is from the movie. Actually, all of the clips available have embedding disabled. So this is just a picture of that clip. If you want to see it, go to the youtube version.
One other spoiler: Sauron is really Frodo's…
rallain | June 3, 2010Reader Colin asked a great question about this popular clip.
How fast was the car moving?
First, a quick assumption. I will assume that the frame rate on the video is correct (meaning not slowed down). Colin already looked up the length of the Chevy Impala on Wikipedia for me. It has a length of 5.09 meters (I need that to scale the video).
This is the data I get from Tracker Video. The graph below is the x-position of the car with a line fit to the part of the motion before it hit the "ramp". Note that since the car is moving to the left, it has a negative x-velocity.
So, this says the…
rallain | May 3, 2010This video seems like it is getting popular, but maybe that is because it is so awesome.
Maybe it is just me, but I find this video very visually satisfying. I love the way they compare the different runners.
Anyway, there is some physics here. Commenter Ben sent me the link to this video (thanks!) with some great questions. Which of the runners has a greater kinetic energy? What about the power? These aren't too difficult to answer, but the first thing is to get the data. There are several options (including just using a stop watch). But no, that is not good enough for me. Instead, I…
edyong | March 22, 2010Like it or not, the golden arches of McDonalds are one of the most easily recognised icons of the modern world. The culture they represent is one of instant gratification and saved time, of ready-made food that can be bought cheaply and eaten immediately. Many studies have looked at the effects of these foods on our waistlines, but their symbols and brands are such a pervasive part of our lives that you'd expect them to influence the way we think too.
And so they do - Chen-Bo Zhong and Sanford DeVoe have found that fast food can actually induce haste and impatience, in ways that have nothing…
edyong | February 28, 2010We've all experienced the agonising wait for feedback, whether it's for exam grades, news from a job interview, or results from a grant application. These verdicts can have a massive influence in our lives but they can often take weeks or even months to arrive. And that's a big problem, according to Keri Kettle and Gerald Häubl from the University of Alberta.
They have found evidence that we do better at tasks the sooner we expect news about our performance. If we think we'll be evaluated quickly, the threat of a negative appraisal looms ever larger. And this greater sense of danger…
rallain | January 31, 2010This is really random, but quick. I was channel surfing and saw the end of the movie: Fantastic 4 - Rise of the Silver Surfer. SPOILER: At the end someone really big explodes in space. There, that wasn't too much of a spoiler, was it? (unless you read the title)
I know I am a loser. I initially thought: wow, that seemed pretty fast for that scale. I wonder if that exploding stuff was going faster than the speed of light. OH! I know, I will use Tracker to measure it. It is video that is set for analysis since it has the Earth in there - and I am pretty sure I know how big that is.…
rallain | August 23, 2009I saw this video on digg or reddit. I can't remember which.
I was in awe. Then I started thinking. I wonder how fast that water was moving up right after the explosion. Too bad the video doesn't have a scale. Well, it kind of does - there is that ship. I am terrible at ship identification though. Maybe I can use my favorite scaling trick - assume the stuff is on the surface of the Earth. This means that free falling objects would have an acceleration of -9.8 m/s2. Let me try this on the water as it falls. Oh, trust me. I know it is not really free falling, but it is in this big…
esiegel | April 24, 2008Warning: Crazy talk ahead. Some of you may remember that I wrote about inflation and why its alternatives fail awhile back. Apparently, Louise Riofrio didn't get the memo. When there's misinformation about cosmology out there, it's up to me to set the record straight. (And I am not alone.) Let me first remind you about one of the alternatives to inflation I debunked last month:
Add defects and vary the Speed of Light. This one’s out. Why? Because we would see defects in the Cosmic Microwave Background, and we don’t. The constancy of the speed of light is highly supported by experiments, but…