Physics

Physics

Problem

A 3 kg3\,\text{kg} trolley moving at 6 m s−16\,\text{m s}^{-1} collides head-on with a 2 kg2\,\text{kg} trolley that is at rest. After impact the first trolley moves at 2 m s−12\,\text{m s}^{-1} in the original direction and the second at 6 m s−16\,\text{m s}^{-1} in the same direction. What is the coefficient of restitution for this collision? a) 0.500.50 b) 0.670.67 c) 1.001.00 d) 0.330.33
Intuitive explanation

The coefficient of restitution measures how much kinetic energy is "bounced back" in a collision—it's the ratio of relative velocity of separation to relative velocity of approach. You'll use the definition e=relative velocity afterrelative velocity beforee = \frac{\text{relative velocity after}}{\text{relative velocity before}}, being careful to treat velocities as signed quantities (positive in one direction, negative in the other). This tells you whether the collision is elastic (e=1e=1), partially elastic (0<e<10 < e < 1), or perfectly inelastic (e=0e=0).

Intuitive explanation

The coefficient of restitution measures how much kinetic energy is "bounced back" in a collision—it's the ratio of relative velocity of separation to relative velocity of approach. You'll use the definition e=relative velocity afterrelative velocity beforee = \frac{\text{relative velocity after}}{\text{relative velocity before}}, being careful to treat velocities as signed quantities (positive in one direction, negative in the other). This tells you whether the collision is elastic (e=1e=1), partially elastic (0<e<10 < e < 1), or perfectly inelastic (e=0e=0).

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