Question

The velocity of moving body of mass 10 kg is changed from 20m/s to 10m/s. What is the change in K.E?

Answer 1

Answer:

Mass of the body =10 kg

Initial velocity u=4 m/s

Final velocity v=8 m/s

Time t=2s

a) Momentum before force acts p1=m×u=10×4=40kg.m/s

b) Momentum after force acts p2=m×v=10×8=80kg.m/s

c) Gain in momentum per second =240=20kg.m/s

d) Acceleration a=tv−u=28−4=2m/s2

Force =m×a=10×2=20 N