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JEE Main · 2025 · 04 Apr 2025 · Shift 1 · Gravitation

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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 m 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✓ Correct
  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

Answer: (A)

Solution

The kinetic energy needed to just reach infinity equals the escape energy. With escape speed ,
not , so the assertion is false. Taking the gravitational potential energy as zero at infinity is the standard convention, and since it is negative everywhere nearer the Earth, zero is indeed its greatest value, so the reason is true. The assertion is false while the reason is true.

JEE Main · 2025 · 04 Apr 2025 · Shift 1 · Single correct option

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