Question

A 75.0 kg object decelerates from a speed of 100 m/s to 50 m/s over an interval of 25 seconds. What was the net force acting upon the object that caused this change in momentum?​

Answer 1

Assuming constant acceleration a, the object has undergoes an acceleration of

a = (50 m/s - 100 m/s) / (25 s) = -2 m/s²

Then the net force has a magnitude F such that, by Newton's second law,

F = (75.0 kg) a

F = (75.0 kg) (-2 m/s²)

F = -150 N

meaning the object is acted upon by a net force of 150 N in the direction opposite the initial direction in which the object is moving.