Velocity physics 101

Question

You drop a rock off a bridge. When the rock has fallen 4 m, you drop a second rock. As the two rocks continue to fall, what happens to their velocities?

(a) Both increase at the same rate.

(b) The velocity of the first rock increases faster than the velocity of the second.

(c) The velocity of the second rock increases faster than the velocity of the first.

(d) Both velocities stay constant.

Answer 1

What's important to consider is that objects in free-fall always accelerate downward at a rate of g = 9.81 m/s^2 (if we ignore air resistance).

Acceleration is defined as the rate of change of velocity, so the velocities of both rocks will be increasing at the same rate. Because of this, we can confidently choose answer (a).