Question

An object of mass 1kg is subjected to a variable force in x-direction. The force function is F = x^2 N. What is the work done in moving the object from x = 2 to 5?

(a) 40

(b) 39

(c) 38

(d) 69

I have been asked this question in unit test.

My question comes from Work Done by a Variable Force in section Work, Energy and Power of Physics – Class 11

Answer 1

Right answer is (b) 39

Easy explanation: The work is given by formula W = \(\int_{x1}^{x2}\)F * dx. So, W = \(\int_{2}^{5}\)x^2 * dx = (5^3-2^3)/3 = 39 J.