PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
Two low-friction carts, X and Y, sit on a horizontal air track. Cart X has mass 0.50 kg and is moving due east at 2.0 m s⁻¹, while cart Y has mass 0.75 kg and is moving due north at 1.5 m s⁻¹. Immediately before they collide, the carts form an isolated system (net external force ≈ 0).
Using only a graphical treatment of momentum vectors—without performing any numerical component calculations—answer the following questions about the system’s motion.
(a) On blank axes you provide, draw to scale the momentum vector for each cart and arrange them head-to-tail to represent the system’s total momentum just before the collision. Clearly label each vector and indicate your scale.
(b) Without computing any numbers, use the diagram you created in part (a) to predict the general compass direction (e.g., “north-of-east,” “south-of-west,” etc.) in which the joined carts will move immediately after they stick together.
(c) Describe two distinct features of your vector diagram that support the conclusion that linear momentum is conserved during the collision.