(a) As velocity of the object at t = 0 s is zero, the initial momentum of the object will also be zero.

(b) At t = 1s, the velocity of the object will be 9.8 ms^{–1} [use v = v_{0} + at] pointing downward. So the momentum of the object will be

p_{1 }= (2 kg) × (9.8 ms^{–1}) = 19.6 kgms^{–1} pointing downward.

(c) At t = 2 s, the velocity of the object will be 19.6 m s^{–1} pointing downward. So the momentum of the object will now be

p_{2} = (2 kg) × (19.6 ms^{–1}) = 39.2 kgms^{–1} pointing downward.

Thus, we see that the momentum of a freely-falling body increases continuously in magnitude and points in the same direction. Now think what causes the momentum of a freely-falling body to change in magnitude?