a 65-kg astronaut pushes against the inside back wall of a 2000-kg spaceship and moves towards the front. the push lasts for 0.30s and changes her speed from 0 to 1.6 m/s. draw momentum bar charts to represent this process for the systems consisting of (a) only the astronaut, and (b) only the spaceship. determine the force the astronaut exerts on the spaceship and the velocity of the spaceship after the astronaut is finished pushing it.