Question

A boy of mass 50g runs a step of 5m each in 2mins.find the work done by the boy

Answer 1

Let $m=50g = 0.05kg$. The work done against gravity is then:

$$W = mgh$$

where $h = 5m$ is the height, $g = 9.8m/s^2$ is the gravitational acceleration. Thus, obtain:

$$W = 0.05kg\cdot 9.8m/s^2\cdot5m = 2.45J$$

ANswer. 2.45 J.