21
votes
6answers
2k views

Why are rockets so big?

I'm curious why rockets are so big in their size. Since both the gravitational potential one need to overcome in order to put thing into orbit, and the chemical energy burned from the fuel, are ...
-3
votes
1answer
97 views

How fast will I get if I burn a comet? [closed]

Assuming I have a spacecraft which is $30,000\,\mathrm{kg}$ (roughly the size of the Apollo spacecraft). If I take a comet and (theoretically) electrolize it perfectly to hydrogen and oxygen. I know ...
3
votes
3answers
418 views

Conservation of Energy in Different Frames of Reference

Say I have a bucket of fuel that can produce 150J of energy by combustion. No matter what frame of reference an observer or the bucket of fuel is in, since the configuration of molecules stay the ...