NDA 2026 · PYQ · Gravitation / Potential and Field · medium
In a gravitational field, the gravitational potential at two points A and B is the same for a body; however, the gravitational field at these two points is not the same. Which one of the following is correct?
A.Positive work is done by gravity in taking the body from point A to point B
B.Negative work is done by gravity in taking the body from point A to point B
C.Gravity must be non-conservative in such a field
D.No work is done by gravity in taking the body from point A to point B✓ Correct
Explanation
The work done by a conservative force like gravity in moving an object between two points equals the negative of the change in potential energy: W = -ΔU = -m(V_B - V_A), where V is the gravitational potential. Since the gravitational potential is the same at both points A and B (V_A = V_B), the work done by gravity is W = -m(V_B - V_A) = 0. The fact that the gravitational field differs at the two points doesn't affect this; only the potential difference matters for work. Gravity remains conservative regardless. Therefore, no work is done by gravity in taking the body from A to B.
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