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Question
During inelastic collision between two bodies, which of the following quantities always remain conserved?
Options
Total kinetic energy.
Total mechanical energy.
Total linear momentum.
Speed of each body.
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Solution
Total linear momentum.
Explanation:
If in a collision kinetic energy after collision is not equal to kinetic energy before the collision, the collision is said to be inelastic.
Coefficient of restitution 0 < e < 1
When we are considering the two bodies as systems the total external force on the system will be zero.
Hence, the total linear momentum of the system remains conserved.
Here kinetic energy appears in other forms, i.e. energy may be lost in the form of heat and sound etc. In some cases
`(KE)_"final" < (KE)_"initial"` such as when initial KE is converted into internal energy of the product (as heat, elastic or excitation) while in other cases `(KE)_"final" > (KE)_"initial"` such as when internal energy stored in the colliding particles is released.
Examples: (1) The collision between two billiard balls.
(2) The collision between two automobiles on a road.
In fact, the majority of collisions belong to this category.
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