Question

An object is taken from a point P to another point Q in a gravitational field.

• A. Assuming the earth to be spherical, if both P and Q lie on the earth's surface, the work done is zero
• B. If P is on the earth's surface and Q above it, the work done is minimum when it is taken along the straight line PQ
• C. The work done depends only on the position of P and Q and is independent of the path along which the particle is taken
• D. There is no work done if the object is taken from P to Q and then brought back to P along any path

Answer 1

Answer: (A), (C), (D)

The correct options are
A Assuming the earth to be spherical, if both P and Q lie on the earth's surface, the work done is zero
C The work done depends only on the position of P and Q and is independent of the path along which the particle is taken
D There is no work done if the object is taken from P to Q and then brought back to P along any path

Gravitational field is conservative $\Rightarrow$work done to move an object in closed loop$=0$

And work done in moving a mass from one location to another is independent of path.

$\therefore A,C$ and $D$ are correct.