Question

For how long should a force of 100N act on a body of 20kg so that it acquires a velocity of 100m/s?

Answer 1

Given,  

Force, F = 100 N  

Mass of the body, m = 20 kg  

Therefore, Acceleration is given by,  

Acceleration, a = F/m = 100/20 5m/s^2  

Now, Initial velocity, u = 0  

Final velocity, v = 100 m/s  

Acceleration, a = 5m/s^2  

Therefore, Time for which the force is applied,  

t = v-u/a = 100 - 0/5  

= 20s

Answer 2

F=ma

F=m(v-u)/t

therefore Ft=mv-mu

mass=20kg

Force=100N

Initial velocity=0m per sec

Final velocity=100m per sec

Rest is in the pic