I am wondering how Newton's 3rd Law of Motion would apply in the case of a man walking the length of a rotating spacecraft.
Please reference the drawing below.
Say that there was a spacecraft sitting still in interstellar space, far away from any stars and planets. The spacecraft then starts to rotate via an electric motor until it reaches a rotating speed that will mimic Earth's gravity for a man inside the spacecraft. The man walks from one end of the spacecraft to the other end. While he is walking, will the spacecraft remain stationary or will the spacecraft move in the opposite direction, thus obeying Newton's 3rd Law of Motion, for every action there is an equal and opposite reaction.
Also, if the spacecraft is set in motion by the man's walking, will the spacecraft remain in motion and travel in that direction indefinitely?
If the length of this spacecraft is extended out to 1 km long and the man is walking at 3km/hour, at this rate it will take him 20 minutes to walk from one end to the other. Now since he transferred a lot of kinetic energy to the spacecraft in those 20 minutes, the spacecraft should be moving at a good rate of speed (based on the fact that the spacecraft is constantly accelerating while he is walking).
When he reaches the other end and comes to a stop, will his body mass coming to a stop transfer enough kinetic energy back to the spacecraft to bring the spacecraft to a stop?