Question

Consider the rocket plus fuel to be your system. If the system is the rocket is initially in space and fueled but not moving relative to your point of observation, show that the law of conservation of linear momentum proves that if the fuel is burned and moves in one direction that the rocket MUST move in the opposite direction. (hint: start with pintial = pfinal)

Answer 1

no external forces so momentum before and after must be zero.

0 = mf vf + mr vr
vr = - mf vf/ mr

Answer 2

thanks again!