A body of mass 2 kg moving at 3 m per second collides and sticks to a stationary body of mass 4 kg. Their common velocity is
Correct answer: A. 1 m per second
- A. 1 m per second
- B. 1.5 m per second
- C. 0.5 m per second
- D. 3 m per second
Explanation
Total momentum before is 2 multiplied by 3, that is 6 kg m per second, and the combined mass afterwards is 6 kg, so the common velocity is 1 m per second. The kinetic energy falls from 9 J to 3 J, the difference going into heat and deformation. Momentum is conserved even though energy is not.
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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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