PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
Two low-friction carts, A and B, move on a straight horizontal track. Cart A has mass mA=0.50kg and initially moves to the right at v0=2.4ms−1. Cart B has mass mB=1.0kg and is initially at rest. The facing ends of the carts are covered with Velcro so that they stick together during the brief impact.
Assume external horizontal forces are negligible during the collision.
(1) Derive an algebraic expression for the speed vf of the combined carts immediately after impact in terms of mA, mB, and v0.
(2) Calculate the numerical value of vf for the given masses and initial speed.
(3) Determine the initial kinetic energy of the system, the kinetic energy immediately after the collision, and the percentage of the initial kinetic energy that is lost during the collision.
(4) The experiment is repeated with the same initial speed v0, but the masses of the two carts are swapped (cart A now has 1.0kg and cart B 0.50kg). Without repeating detailed calculations, rank the two trials according to the percentage of kinetic energy lost (greatest to least) and justify your ranking qualitatively or quantitatively.
(5) Discuss two physical mechanisms by which the kinetic energy lost in these impacts could be transformed into other forms of energy.