A student analyzes a system consisting of two carts on a track
PHYSICS · Single correct · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
A student analyzes a system consisting of two carts on a track. Cart X moves north, Cart Y moves east, and the student claims, “Because each cart carries momentum, the system’s net momentum must also be in either the north or the east direction.”
Which statement best evaluates the student’s claim?
(a) It is correct because the perpendicular momentum components cancel, giving the system zero net momentum.
(b) It is incorrect because momentum vectors add, so the net momentum can point in a direction different from either cart’s motion.
(c) It is correct because momentum is conserved separately along each axis, so the larger component dictates a net momentum that must be either north or east.
(d) It is incorrect because momentum is a scalar quantity; only kinetic energy has direction.