Three identical steel balls A, B and C of mass 50 g are projected normally on to the…
PHYSICS · Multi-part · CBSE · Physics · Laws of Motion · Laws of Motion
Problem
Three identical steel balls A, B and C of mass 50 g are projected normally on to the same smooth vertical wall from the same position. The initial speeds are 2 m s⁻¹, 3 m s⁻¹ and 4 m s⁻¹ respectively. Each ball rebounds along its own line of approach with the same speed with which it struck the wall. Air resistance is negligible and the duration of contact with the wall is the same for all three balls.
(i) Explain, without using numerical calculation, why the direction of the impulse on every ball is horizontally reversed during the collision.
(ii) Using suitable reasoning, arrange the magnitudes of the impulses on the three balls in ascending order.
(iii) Comment on whether the impulse delivered by the wall on a ball is equal in magnitude and opposite in direction to the impulse delivered by the ball on the wall. Give a brief justification based on Newton’s laws.