PHYSICS · Subjective · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
Two students, A and B, wearing ice skates stand face to face on a perfectly frictionless frozen lake. Student A has mass 50kg and student B has mass 60kg. While at rest they push each other’s hands so that A exerts a force of 100N on B for 0.40s.
(a) What is the force experienced by student A during the push? State its direction relative to the force exerted on B.
(b) Calculate the acceleration of each student during the interaction interval.
(c) Determine the speed acquired by each student immediately after their hands lose contact.
(d) Show by calculation that the total momentum of the two-student system remains zero after they separate.
(e) Briefly explain how this result is consistent with Newton’s third law of motion.