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JEE Main 2025 Jan 28 Shift 1, Physics Q11: Work Energy Theorem And Its Applications

JEE Main2025Jan 28, Shift 1Physics
Q.

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R

Assertion A: In a central force field, the work done is independent of the path chosen

Reason R: Every force encountered in mechanics does not have an associated potential energy.

In the light of the above statements, choose the most appropriate answer from the options given below

  1. A

    A is true but R is false

  2. B

    Both A and R are true but R is NOT the correct explanation of A

  3. C

    Both A and R are true and R is the correct explanation of A

  4. D

    A is false but R is true

Solution

Assertion A: A central force field is conservative; the work it does between two endpoints depends only on the endpoints and not the path. True.

Reason R: Friction and other non-conservative forces have no associated potential energy. So the general statement "every force in mechanics has an associated PE" is false — i.e. "every force does not have an associated PE" is a correct general statement. True.

However, the truth of R is a statement about non-conservative forces in general, not specifically an explanation for why a central force field is path-independent. The justification for A is that a central force is conservative (curl-free), which is a separate (positive) statement, not the (negative) statement in R.

Both A and R are true, but R is not the correct explanation of A.

Concept behind this question

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