Assertion (A) In an elastic collision of two billiard balls, the total KE is conserved during the short time…

Assertion(A) In an elastic collision of two billiard balls, the total KE is conserved during the short time of collision of the balls (i.e., when they are in contact).Reason(R) Energy spent against friction does not follow the law of conservation of energy. Codes
  1. Both A and R are true and R is a correct explanation for A.
  2. Both A and R are true but R is not a correct explanation for A.
  3. A is true but R is false.
  4. Both A and R is false.

Solution

In an elastic collision of two billiard balls, there is deformation in shape of balls momentarily. During the collision potential energy increases due to deformation of balls and kinetic energy decreases. Hence, total energy remains constant but kinetic energy is not conserved. Law of conservation of energy always applies, in every case. Thus, both Assertion and Reason are false.

Asked in: AP EAMCET 2021 (25 Aug Shift 2)

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