Question

As Pluto moves from the perihelion to the aphelion, the work done by gravitational pull of Sun on Pluto is

• A. is zero
• B. is positive
• C. is negative
• D. depends on sense or rotation

Answer 1

The correct option is C is negative

As gravity is an attractive force and acts towards the centre of sun.Now taking Pluto from the perihelion to the aphelion means it is moving away from Sun, thus from $W=\overrightarrow{f}.\overrightarrow{s}$ implies that work done by gravitational force has to be negative.