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JEE Main 2025 Apr 4 Shift 1, Physics Q14: Gravitational Potential, Potential Energy And Work Done

JEE Main2025Apr 4, Shift 1Physics
Q.

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

Assertion A : The kinetic energy needed to project a body of mass from earth surface to infinity is , where is the radius of earth.

Reason R : The maximum potential energy of a body is zero when it is projected to infinity from earth surface.

In the light of the above statements, choose the correct answer from the option given below

  1. A

    A False but R is true

  2. B

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

  3. C

    A is true but R is false

  4. D

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

Solution

The minimum KE to escape to infinity equals the magnitude of the gravitational PE at the surface: (using ). This is the escape kinetic energy, not . So Assertion A is false.

By the standard convention, the gravitational PE is taken to be zero at infinity, and is negative everywhere closer to the earth. So the maximum PE (least negative, equal to zero) is indeed at infinity. Reason R is true.

A is false but R is true — option (1).

Concept behind this question

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