conservation of momentum

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 weight: 50 kg (you know, kids and stuff) Average vertical jump (center of mass): 0.3 meters - and I think that is generous. Mass of the Earth: 6 x 1024 kg Gravitational field near the surface of the Earth is constant with a magnitude of 9.8 N/kg Ignore the interaction with the Sun and…

I think we are entering a new era. An era where it is quite simple to find and get great videos. Oh, just saw a great tackle on the TV? In the old days, you would have to get that video off the TV yourself. Not anymore. Welcome to the interwebs. Also, the quality is awesome compared to 10 years ago. Here is the video. Yes, I know this is from several weeks ago - I am slow. Also, thanks to the person that put this on youtube - I edited your clip to remove the music and just look at the one collision. You did a good job though. In terms of video analysis, this isn't too bad of a video…