A wooden block of mass slides on a horizontal track toward a light horizontal spring…
PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
A wooden block of mass 2.0kg slides on a horizontal track toward a light horizontal spring fixed to a rigid wall. The initial speed of the block when it is 0.80m from the spring is 3.0ms−1. The coefficient of kinetic friction between the block and the track is μk=0.10, and the spring constant is k=200Nm−1. The block eventually comes momentarily to rest after compressing the spring.
Three different choices of system boundaries are proposed:
• System I: the block alone.
• System II: the block plus the spring.
• System III: the block, the spring, and the portion of track on which the block slides.
Answer the following questions. (No numerical calculation is required unless explicitly stated.)
(a) For each of the three system choices, list the forms of energy that can be stored internally. Explain your reasoning.
(b) For System I, is the total mechanical energy of the system conserved during the motion? Justify your answer by identifying any energy transfers that cross the boundary.
(c) Repeat part (b) for System II.
(d) Repeat part (b) for System III and state which of the three system choices yields the simplest conservation statement for analyzing the block’s motion. Justify your selection.