question_answer

A 100 g iron ball having velocity 10 m/s collides with a wall at an angle 30° and rebounds with the same angle. If the period of contact between the ball and wall is 0.1 second, then the force experienced by the wall is            [CPMT 1997]

A)  10 N  

B)                           100 N            

C)                         1.0 N            

D)                         0.1 N

Correct Answer: A

Solution :

                            During collision of ball with the wall horizontal momentum changes (vertical momentum remains constant)             \[\therefore \]\[F=\frac{\text{Change in horizontal momentum }}{\text{Time of contact}}\]                    \[=\frac{2P\cos \theta }{0.1}=\frac{2mv\cos \theta }{0.1}\]             \[=\frac{2\times 0.1\times 10\times \cos 60{}^\circ }{0.1}\]\[=10\ N\]