Certain force acting on a 20 kg mass changes its velocity from 5 ms⁻¹ to 2 ms⁻¹. Calculate the work done by the force.

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 = 1/2 m (v² - u²)
W = 1/2 × 20 × (2² - 5²)
W = -210 J