Practice question · Multiple choice
Momentum is conserved in every collision but kinetic energy only in elastic ones. Why do the two conservation laws behave differently?
Hints
- Ask what happens to the shape of two cars that crash.
- One law depends on Newton’s third law; the other on where the energy can go.
Show the answer
B. Because internal forces cancel while energy can become heat
Why
Momentum has nowhere else to go; energy does. That is why momentum conservation is the reliable tool for analysing collisions and energy is not.
Practise Linear Momentum, Impulse, and Collisions
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