A pendulum is hanging from the ceiling of a train car. a) When the train is stationary, what direction does the pendulum hang? b) When the train is moving forward at a steady speed along a straight track, what direction does the pendulum hang? c) When the train is speeding up as it goes forward, what direction does the pendulum hang? d) When the train is moving at constant speed around a curved track, what direction does the pendulum hang?