Recent content by DavidDoakes

Thank you for clearing this up for me. Doesn't it bother you that so many sources explain this incorrectly (or at least in such a way that it's easy to interpret it incorrectly)?

I'd say both the astronaut and rock would have speeds of 0.707 m/s relative to the observer (otherwise you can could catch both the astronaut's and the rock's kinetic energy, transport it to the center of the system and use half of it to repeat the whole thing, gaining 50 joules of free energy...

I have a quick question on Newton's third law. When a 100kg astronaut in space is holding a 100 kg rock and then pushes it away from him with 50 joules of energy (the kinetic energy put into the system) and a second astronaut (observer) is watching, sitting still relatively to the location...