Which of the motions described below are nonuniform? Explain your choices

a) A rubber stopper is dropped from your raised hand to the floor.
b) A car is travelling at a steady rate of 85km/h due west.
c) A rocket begins rising from the launch pad.
d) A motorcycle rider applies the brakes to come to a stop.

a) Uniform
b) Uniform
c) Nonuniform. Because as the rocket begins to rise, its speed is increasing.
d) Nonuniform. Because as the motorcycle stops, its speed decreases to zero.