A student stands on a rolling platform that is initially at rest on a level
PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
A 60kg student stands on a 40kg rolling platform that is initially at rest on a level, frictionless surface. The student throws a 0.50kg ball horizontally with a speed of 5.0ms−1 relative to Earth.
Neglect air resistance.
(a) Choose an appropriate system to analyze the throw, and determine the speed of the platform (with the student on it) immediately after the ball leaves the student’s hands.
(b) Explain why any external horizontal forces on the system you chose in part (a) are negligible during the brief throwing interval.
(c) After the throw, the student quickly bends down and catches the ball, bringing it to rest relative to the platform in 0.20s. Qualitatively describe what happens to the platform’s speed during the catch and justify your description using momentum arguments.