An ice skater (considered as a particle for this analysis) of mass is initially at…
PHYSICS · Multi-part · AP · Physics 1: Algebra-based · Linear Momentum · Linear Momentum
Problem
An ice skater (considered as a particle for this analysis) of mass 65kg is initially at rest on a frictionless frozen lake. She throws a 0.20kg snowball horizontally. You define the +x-axis to point in the direction the snowball travels.
• Snowball speed relative to the skater at the instant of release: 12ms−1
Ignore air resistance during the brief throw.
(a) Explain qualitatively, without numbers, why the snowball’s momentum must be equal in magnitude and opposite in direction to the skater’s momentum at the instant it leaves her hands.
(b) Using your axis choice, calculate the momentum (magnitude and sign) of the snowball immediately after release relative to the ice surface.
(c) Determine the skater’s speed and direction (include sign) immediately after the snowball is released.
(d) Another observer on the opposite shore chooses +x to point opposite your original direction. Discuss how the numerical signs of the momenta for both the snowball and the skater would change in that observer’s calculations, and explain why both observers still agree on the physical situation.