A force is applied on a body of mass 20 kg moving with a velocity of 40 m/s . The body attains a velocity of 50 m/s in 2 seconds . Calculate the work done by the body.

A
900 J
B
9000 J
C
18000 J
D
1800 J
Answer:

The correct option is B. CORRECT OPTION

Note
The correct option is B 9000 J We have the initial velocity u = 40 m/s and final velocity v = 50 m/s Using work energy theorem Work done by the force ( W ) = Change in kinetic energy W = 1 2 m v 2 − 1 2 m u 2 W = 1 2 × 20 ( 50 2 − 40 2 ) = 10 × ( 50 2 − 40 2 ) = 10 × 900 W = 9000 J Hence option B is the correct answer