Question

A force acts on a rest body of mass 2 kg for 5 sec and then force ceases to act and the body moves 80m during 4 sec.Find how much force has applied on the body?

Answer 1

after the force stops acting the body will move with a constant velocity. So then

t=4s

S=80m

v=80/4=20 m/s

when force was acting

u=0 initially body was at rest

v=20 as force was removed

t=5s

a=(v-u)/t= 4m/s2

F=ma=4*2=8N