PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
Two laboratory carts, each of mass 0.50kg, collide head-on on a level, low-friction track. Before the collision, Cart 1 moves at 0.80ms−1 to the right (measurement uncertainty ±0.02ms−1), while Cart 2 is at rest. When the carts collide, they lock together by a strong hook-and-loop mechanism and move off as a single unit at 0.38ms−1 to the right (measurement uncertainty ±0.02ms−1). Neglect other external forces during the short collision.
(a) Using the central (stated) velocity values, compute the total kinetic energy of the system just before the collision.
(b) Using the same central values, compute the total kinetic energy of the joined carts immediately after the collision.
(c) Calculate the percentage change in kinetic energy for the event.
(d) Estimate the percent uncertainty in each kinetic-energy calculation, assuming the only significant uncertainty arises from the stated uncertainties in speed and that kinetic energy depends on the square of speed.
(e) Decide whether the observed change in kinetic energy is statistically significant relative to the combined uncertainties. Then classify the collision and defend your conclusion in two or three well-structured sentences.