A rubber ball slides across a frictionless horizontal surface toward a movable wall…
PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
A 0.20kg rubber ball slides across a frictionless horizontal surface toward a 2.0kg movable wall that is attached to a light horizontal spring. The ball moves to the right with speed 4.0ms−1 just before making contact with the wall. During the 0.025s contact interval, the spring exerts an average force of 150N on the wall toward the right and, by Newton’s third law, an equal-magnitude force toward the left on the ball. After separating from the wall, both objects continue to slide freely.
(a) For a system that consists of the ball only, identify the external forces acting during the 0.025s contact interval.
(b) For a system that consists of the ball, wall, and spring together, explain whether linear momentum is conserved during the contact interval.
(c) Using an appropriate choice of system, calculate the speed and direction of the ball immediately after it loses contact with the wall.
(d) Suppose instead that the wall is rigidly attached to Earth and cannot move. Qualitatively describe how, if at all, your answer to part (c) would change, and provide a physical explanation rooted in forces and momentum.