A steel pellet is fired horizontally at into a wooden block that is initially at rest…
PHYSICS · Multi-part · CBSE · Physics · Work, Energy and Power · Work, Energy and Power
Problem
A 15g steel pellet is fired horizontally at 320ms−1 into a 2.0kg wooden block that is initially at rest on two different horizontal surfaces.
• Trial 1: The block rests on a nearly friction-free air track.
• Trial 2: The block rests on a rough tabletop that exerts a horizontal kinetic-friction force of magnitude 6.0N on the block at all times.
Assume the pellet embeds completely in the block during an impact interval of 1.8ms. Ignore any motion in directions other than horizontal.
(a) For each trial, describe a choice of system whose total horizontal momentum is constant during the impact. Explain your reasoning in terms of the horizontal forces acting during that interval.
(b) For each trial, state whether the horizontal momentum of the pellet–block combination alone is conserved during the impact. Justify your answer using the forces identified in part (a).
(c) Without performing calculations, predict whether the common speed of the pellet–block immediately after impact will be the same, larger, or smaller in Trial 2 than in Trial 1. Support your prediction with qualitative reasoning based on momentum principles.