A steel ball bearing of mass m1 and speed of magnitude v1 has a head-on elastic collision with a steel ball bearing of mass m² at rest. Rank the speed v1 of m1 relative to v2, the magnitude of the speed of m², after the collision when: i) m1 m²; ii) m1 = m²; and iii) m1 v2

Question

A steel ball bearing of mass m1 and speed of magnitude v1 has a head-on elastic collision with a steel ball bearing of mass m² at rest. Rank the speed v1 of m1 relative to v2, the magnitude of the speed of m², after the collision when: i) m1 > m²; ii) m1 = m²; and iii) m1 < m². A)v1 < v2; v1 < v2; v1 < v2 B)v1 < v2; v1 = v2; v1 > v2 C)v1 < v2; v1 > v2; v1 > v2 D)v1 > v2; v1 = v2; v1 < v2 E)v1 > v2; v1 > v2; v1 > v2

Quizplus · Accepted Answer

In an elastic collision, momentum and kinetic energy are conserved. i) When m1 > m2, m1 will slow down and m2 will gain speed, so v1 < v2. ii) When m1 = m2, they exchange velocities, so v1 = v2. iii) When m1 < m2, m1 will bounce back and m2 will move forward, so v1 > v2.

A Steel Ball Bearing of Mass M1 and Speed of Magnitude