Question

Q3. A man lifts a mass of 20 𝑘𝑔 to a height of 2.5 𝑚. Assuming that the force of gravity on 1 𝑘𝑔 mass is 10 𝑁, find the work done by the man. [2 Marks]

Answer 1

Given, Mass (m) = 20 kg and height (h) = 2.5 m

Step 1: Find the force of gravity on 20 kg
Force of gravity on a mass of 1 kg = 10 N
So, force of gravity on a mass of 20 kg (F) = 20 × 10 N = 200 N
[1 Mark]

Step 2: Find work done
Work is done by man against gravitational force.
Work done (W) = F × displacement
W = 200 N × 2.5 m
W = 500 J

Hence, work done by the man is 500 J.
[1 Mark]