energy
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Category archives for energy
What if everyone jumped?
Posted by Rhett Allain on August 26, 2010 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!
Posted by Rhett Allain on August 5, 2010 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…
Paranoia, it’ll destroy ya
Posted by Rhett Allain on July 23, 2010 Check this out – NY Times: No Motors, but Mistrust at Tour de France. So, the short story is that some people claim that Cancellara is cheating by putting a hidden electric motor in his bike. Now they are going to do random hidden-motor checks. I have analyzed this motor-in-a-bike already: Energy in a hidden…
More Dangerous Kids
Posted by Rhett Allain on July 11, 2010 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…
Basics: Electric Potential for a Point Charge
Posted by Rhett Allain on June 15, 2010 Pre Reqs: electric potential, electric field, work-energy To start, remember that for a constant electric field the change in electric potential energy would be: WARNING: that is only for a constant electric field. I know you will be tempted later to use this for a different electric field, but DON’T DO IT. But if not…
Basics: Electric Potential
Posted by Rhett Allain on June 14, 2010 Pre Reqs: Electric Field, Work-Energy, Potential Energy If you are already familiar with the topics listed in the pre-reqs above, this will be uber-simple. Potential energy – short version The work-energy principle basically says: In this most basic form, the energy is just kinetic energy (if you are not going near the speed of light).…
Energy in a hidden battery
Posted by Rhett Allain on June 11, 2010 Back to the discussion about hiding an electric motor in a pro racing cycle. Before, I looked at a video of Fabian Cancellara to see how his speed and acceleration compare to other bikers. The claim on the internet is that he pulls away so fast that he must have a motor hidden in his…
Ask a ScienceBlogger: Drying dishes
Posted by Rhett Allain on June 7, 2010 As part of the Ask a ScienceBlogger series, reader Jim Swanson asks: When I open the dishwasher after washing and the contents are still hot, why do the glass and ceramic items dry off more quickly than the plastic items? This is a great question. Great because it is something most everyone can relate to…
Physics 2 refresher
Posted by Rhett Allain on June 6, 2010 So, I hear you are starting your second semester of physics. One of the cool things about physics is that the second semester still uses stuff from the first semester. Maybe you forgot some of that stuff, so here are the bare essentials you will need to get by (this is assuming you are in…
Why would I think that?
Posted by Rhett Allain on May 31, 2010 So suppose you saw something that looked like this: This is a ball shot out of a shooter device. Well, it is a vypthon animation of a ball. What would you do if you came to see this video? If I had not made it, I would say it is an unrealistic video. It does…