JEE Physics 2023 Question with Solution

Given: A set of statements about work done by different forces.

Find: Which statements are correct.

Use the sign of work from the relation

$$W = \vec{F} \cdot \vec{s} = Fs\cos\theta$$

• For statement (B), gravitational force acts downward while the bucket is lifted upward, so the angle between force and displacement is $180^\circ$. Hence the work done by gravity is negative.
• For statement (E), air resistance always opposes the motion of the pendulum, so its work is negative.
• Statement (A) is incorrect because the man's applied force and the displacement of the bucket are in the same direction, so the work done by the man is positive.
• Statement (C) is incorrect because friction opposes motion, so for a body sliding down an inclined plane the work done by friction is negative.
• Statement (D) is incorrect according to the solution, because on a rough horizontal plane with uniform velocity the applied force is along the displacement, so its work is not zero.

Therefore, the correct statements are (B) and (E). The correct option is D as given in the source solution, although the listed option text shows B and D only, which does not match the solution explanation.