Question

A body of mass 500 g is moving with a speed 10 m/s. A force acts on it which makes it to move with a
speed 20 m/s. Find : (1) the change in kinetic energy of the body, and (ii) the work done by the force on the
body.

Answer 1

Answer:

Given , Mass of object ,m=10 kg

Velocity of object , v=20ms

−1

Initial Kinetic energy , K 1 = 21

×10×20 2 =2000 JNow Final mass ,m 2 =20 kg

Final Velocity , v 2 =10m/s

Final Kinetic energy , K 2 = 21 ×20×10

2 =1000 J

Required Ratio= K 2K 1 = 1000

2000 =2