kinetic energy

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What if everyone jumped?

Might as well jump. Jump. Go ahead, jump. – Van Halen Suppose everyone in the world got together and jumped. Would the Earth move? Yes. Would it be noticeable? Time for a calculation. Note: I am almost certain that I have done this before, but I can’t find where. Starting assumptions. 7 billion people. Average…

Turn or go straight? Quick!

This is a classic problem. You are in a car heading straight towards a wall. Should you try to stop or should you try to turn to avoid the wall? Bonus question: what if the wall is not really wide so you don’t have to turn 90 degrees? Assumption: Let me assume that I can…

In the last episode of MythBusters, they wanted to see if a tornado could make some glass cut off a person’s head. The first attempt was just to take some glass and through it at a simulated human neck. Clearly, this wasn’t quite the same as a tornado. So, here was their plan. If they…

Here is another question from Ask a ScienceBlogger. Reader Uday Panta asks: How does water evaporate in the seas? Doesn’t water evaporate at 100 C? There were some very good responses in the comments where the question was, but I am going to answer it with some more details. Small Particle Model This is where…

A new video from the Red Bull Stratos Jump guys came out. Here it is: This reminds me of an unanswered question about the Stratos jump that I didn’t address on my last post on this topic. Commenter Long Drop asked about how much Felix would heat up as he falls from 120,000 feet. This…

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…

In the last episode of MythBusters, Adam and Jamie wanted to test something that Jamie had said earlier: “Two cars crashing head on at 50 mph is the same as one car crashing into a wall at 100 mph” Jamie was wrong, but that is not what I am going to talk about. Instead, I…

Some People Running

This 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!)…

I already looked at ESPN’s Sport Science episode where they calculate that Marshawn Lynch produces 54,000 watts when pulling some tires. Yes, that is way too high. However, what would happen if some was actually that powerful? What could that person do? How fast could they run 100 meters? That is what I am going…

More ESPN Sport Science Goodness

Let me be clear. I am not really an attacker. If someone wrote a report about ski jumping or something and misused the word “momentum”, no big deal. However, if you have a show that claims to be about SCIENCE and you are obviously putting a lot of money into this show AND a whole…