A 2.5-kg stone is released from rest and falls toward Earth. After 4.0 s, the magnitude of its momentum is:
A) 98 kg · m/s
B) 78 kg · m/s
C) 39 kg · m/s
D) 24 kg · m/s
E) zero

Question

Quizplus · Accepted Answer

The momentum of the stone is calculated using the formula p = mv, where m is mass and v is velocity. After 4 seconds, the velocity v = g*t = 9.8 m/s² * 4 s = 39.2 m/s. Thus, momentum p = 2.5 kg * 39.2 m/s = 98 kg·m/s.

A 25-Kg Stone Is Released from Rest and Falls Toward Earth