0.929c

formula is:

vbe =( vae +vba )/(1+( vae *vba )/c2 )

Fakes. There's no such things about rocket and white stone.

linear momentum.

A rocket works by expelling gases from one end at a very high velocity. The escaping gases have a very high speed and this with their mass translates to a very large momentum. Due to the principle of conservation of momentum the body of the rocket is pushed forward. If both the momentum of the gases as well as that of the rocket are added the sum is zero.

because a rocket makes an explosion that is stopped at one end and so can only go the other way. one of the laws of physics is every action has an equal and opposite reaction which, in this case, moves the rocket.
One word: thrust, when gas is propelled out the back of the rocket it provides the amount of thrust needed to propel the rocket forward.

Newton's third law.