A laboratory cart rests motionless on a horizontal
PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
A 3.0kg laboratory cart rests motionless on a horizontal, frictionless track. Inside the cart is a detachable 0.50kg steel block connected to the cart by a weak spring-loaded mechanism. At t=0s, the mechanism releases, propelling the block horizontally backward (opposite the positive x-direction) at 5.0m/s relative to the ground. The release is completed in a very short time interval, and afterwards the block slides freely on the track independent of the cart.
(1) Part 1: (a) During the release, consider the system consisting of the cart plus the steel block. Identify whether the net external impulse on this system is zero or non-zero. Explain your reasoning.
(2) Part 2: (b) Determine the speed and direction of the 2.5kg remainder of the cart immediately after the block separates.
(3) Part 3: (c) Focusing now on the cart alone (excluding the steel block) as the system, calculate the magnitude of the impulse that the cart receives during the release. Indicate the direction of this impulse.
(4) Part 4: (d) The cart coasts along the track after separation. Describe qualitatively how the momentum of (i) the cart-plus-block system and (ii) the cart alone change, if at all, in the long time interval that follows the release, assuming friction remains negligible.