Question

The work done on a body of mass 5 Kg is 70 J. What is the magnitude of the force applied if the total displacement it covered is 7 m.

(a) 10 N

(b) -10 N

(c) 20 N

(d) 70 N

I got this question at a job interview.

My question is taken from Work in section Work, Energy and Power of Physics – Class 11

Answer 1

Right choice is (a) 10 N

Explanation: The amount of work done on a body is obtained by calculating the dot product of the force and the displacement. Due to lack of information, we assume that the force and the displacement are in the same direction. Since the total work done is given, we can find out the applied force by dividing the total work done by the total displacement. By doing so we get force applied = 10 N.