In an elastic collision between two bodies of equal mass, one moving and one at rest
Correct answer: B. the moving body stops and the stationary one moves off with the original velocity
- A. they stick together
- B. the moving body stops and the stationary one moves off with the original velocity
- C. both move off at half the original velocity
- D. the moving body rebounds
Explanation
Conserving both momentum and kinetic energy for equal masses gives a complete exchange of velocities, which is what makes the Newton's cradle behave as it does and why a cue ball stops dead on a full head on strike. Sticking together would violate energy conservation for an elastic collision. Both moving off at half speed conserves momentum but not kinetic energy.
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About Collisions
Collisions involve the conservation of linear momentum when bodies interact for a short time. The topic covers impulse, elastic and inelastic collisions, kinetic energy changes, and the coefficient of restitution, with calculations usually based on one dimensional motion. Momentum remains conserved in isolated collisions, but kinetic energy is conserved only in elastic collisions.
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