A small toy car of mass 0.20kg rests on the horizontal floor of a train car. The train moves toward the east at constant speed. Suddenly, the train begins to slow down uniformly while still traveling straight.
Assume friction between the toy car’s wheels and the train floor is negligible.
(a) From the perspective of an observer standing on the ground outside the train, describe the net horizontal force acting on the toy car during the interval when the train is slowing down. Justify your answer in terms of the toy car’s motion.
(b) From the perspective of an observer riding inside the train and using the interior of the train as a reference frame, describe what motion (if any) that observer sees for the toy car during the same interval. Explain how the observer’s description is consistent with your answer to part (a).
(c) Indicate whether the toy car is in translational equilibrium during the braking interval, and clearly state the criteria you use to make this determination.