Question

The average resisting force that must act on a 5 kg mass to reduce its speed from 65cm/s to 15cm/s in 0.2s is

A) 12.5 N

B) 25 N

C) 50 N

D) 100 N

Answer 1

A) 12.5 N

Explanations:

Fdt = mv-mu from work energy theorem

F = m( v-u)/dt = 5(65-15)/0.2*100 = 5*50/20 = 12.5 N