PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
Two wheeled carts, A and B, rest on a level, nearly frictionless track. Cart A has mass 1.5kg; cart B has mass 2.5kg and is 1.2m to the right of cart A. Beginning at t=0s, a student pushes horizontally on cart A with a constant 4.0N force directed toward cart B. The push lasts for 0.80s, after which the student’s hand loses contact with the cart. The carts subsequently collide and latch together by Velcro. Treat the collision as taking negligible time compared with 0.80s. Ignore friction and rotational effects.
(a) For the time interval 0≤t≤0.80s, treat cart A alone as the system. Calculate the magnitude of the impulse delivered to cart A by the student’s hand.
(b) Using your result from part (a), determine the speed of cart A immediately after the push ends but just before it strikes cart B.
(c) For the instant just before impact, define the system as carts A and B together. Determine the speed of the combined two-cart system immediately after they latch.
(d) Focus on the interval of the collision only (from the moment just before contact to the instant just after they latch). For the system defined in part (c), state the magnitude of the net external impulse acting during the collision and justify your answer in terms of the forces involved.