Question

A boy of mass 40kg runs up a height of 30steps each 20cm high. Find the force of gravity acting on the body and the work done by the boy against gravity.

Answer 1

Given :-

A boy of mass 40kg runs up a height of 30steps each 20cm high.

To Find :-

Find the force of gravity acting on the body and the work done by the boy against gravity.

Solution :-

Total distance covered = Total steps × Height of eacj step

⇒ 30 × 20

⇒ 600 cm

As 1 m = 100 cm

600 cm = 600/100 = 6 m

(i) Force

Force = Mass × Acceleration

Force = 40 × 9.8

Force = 392 N

(ii) Work done

Work done = Force × Distance

Work done = 392 × 6

Work done = 2352 J