Question

A person is holding a bucket by applying a force of 10N. He moves a horizontal distance of 5m and then climbs up a vertical distance of 10m. Find the total work done by him?

(a) 50J

(b) 150J

(c) 100J

(d) 200J

The question was asked in an international level competition.

I would like to ask this question from Work, Energy and Power in chapter Nature of Physical World of Engineering Physics I

Answer 1

The correct answer is (c) 100J

To explain I would say: F = 10N, s = 5m, θ = 90°

Work done, W1=Fscosθ = 10×5×cos90° = 0

For vertical motion, the angle between force and displacement is 0°.

Here, F = 10N, s = 10m, θ=0°

Work done, W2=10×10×cos0 = 100J

Total work done = W1+W2 = 100J.