Question

A 0.5 kg ball moving with a speed of 12 m/s strikes a hard wal at an angle of ${30}^o$with the wall. It is reflected with the same speed and at the same angle. If the ball is in contact with the wall for 0.25 seconds, the average force acting on the wall is:-

• A. 96 N
• B. 48 N
• C. 24 N
• D. 12 N

Answer 1

The correct option is C 24 N

$$\begin{array}{c}Accordingtoquestion.............\\ \Delta p=OB\sin {30}^0-\left(-OA\sin {30}^0\right)\\ where\Delta pischangeinmomentum.\\ \Rightarrow \Delta p=mv\sin {30}^0-\left(-mv\sin {30}^0\right)=2mv\sin {30}^0\\ \Rightarrow F\times t=2mv\sin {30}^0\\ \Rightarrow F=\frac{2mv\sin {30}^0}{t}\\ where,\\ m=0.5kg,v=12m/s,t=0.25s\\ so,\\ \Rightarrow F=\frac{2\times 0.5\times 12\times \sin {30}^0}{0.25}=24N\\ \therefore 24N\\ sothattheoptionisC.\end{array}$$