Question

A stationary football is kicked by a player such that it attains a speed of $3\raisebox{1ex}{$m$}\!\left/ \!\raisebox{-1ex}{$s$}\right.$ just after the kick. Find the work done by the player on the ball if the mass of the ball is $100g$.

Answer 1

Step 1: Given data

The initial speed of the ball before kicking $v_i$ = $0\raisebox{1ex}{$m$}\!\left/ \!\raisebox{-1ex}{$s$}\right.$

Velocity attained after the kick $v_f$ = $3\raisebox{1ex}{$m$}\!\left/ \!\raisebox{-1ex}{$s$}\right.$

Mass of the ball m = $100g=0.1kg$

Step 2: Finding work done

According to the work-energy theorem, work done is equal to the change in kinetic energy of the body

Hence, work = Final kinetic energy - Initial kinetic energy

$$\begin{gathered} =(\frac{1}{2}\times m\times {v_f}^2)-\left(0\right) \\ =(\frac{1}{2}\times 0.1\times 3^2)-\left(0\right) \\ =(0.05\times 9) \\ =0.45J \end{gathered}$$

Therefore, the work done by the player on the ball is $0.45J$