Question

7.
A force acting on a 20 kg mass changes
its velocity from 6 m/s to 3 m/s. The
work done by the force is :
A) + 510 J
B) - 510 J
C) - 270 J
D) +270J​

Answer 1

Explanation:

Given :          Initial velocity     u=5  m/s

                      Final velocity     v=2  m/s

The work done is equal to the change in the kinetic energy of an object.

W=21m(v2−u2)

W=21×20×(22−52)

⟹W=−210 J