Question

The orbit of Pluto is much more eccentric than the orbits of the other planets. That is, instead of being nearly circular, the orbit is noticeably elliptical. The point in the orbit nearest to the Sun is called the perihelion and the point farthest from the Sun is called the aphelion. As Pluto moves from the perihelion to the aphelion, the work done by gravitational pull of Sun on Pluto is :
(A) Zero
(B) Positive
(C) negative
(D) depends on sense of rotation

Answer 1

Hint Kepler's three laws of planetary motion can be stated as follows: (1) All planets move about the Sun in elliptical orbits, with the Sun as a foci. (2) A radius vector joining any planet of the Sun is in equal spheres at equal distances for the same time.

Complete step by step solution:
Because the direction of indifference is opposite to the direction of indifference, the gravitational pull.
The force on the planet due to gravity is always towards the Sun. When the planet reaches the point of leisure from the nearest point, the perihelion, the effective displacement is away from the Sun, not towards it. When the force and its displacement are in the opposite direction, the work done by the force is called negative.

So option C is correct

Additional Information:
In the early 1600s, Johannes Kepler proposed three laws of planetary motion. Kepler was able to summarize the carefully collected figures of his patron - Tycho Brahe, with three statements that described the motion of the planets in the Sun-centered solar system. Kepler's attempts to explain the underlying causes of such motions are no longer accepted; However, actual laws are still considered to be an accurate description of the motion of any planet and any satellite.
Kepler's three laws of planetary motion can be described as follows:
The path of the planets about the Sun is elliptical in shape, with the center of the Sun at a focus. (Law of Ellipses)
An imaginary line drawn from the center of the Sun to the center of the planet will eject equal areas in equal intervals of time. (Law of equal areas)
The ratio of the squares of the periods of any two planets is equal to the ratio of their average distance from the Sun to the cubes. (Harmon's law).

Note: Pluto's mechanical energy is equal to the sum of the kinetic energy and the potential energy of gravity.
The mechanical energy of the system is conserved when the work done by the external force is zero.
In this question, we have to remember that Kepler's law is applicable for the elliptical orbits. It is clear that all the planets have elliptical orbits. So, Kepler’s law can be applied to find the work done due to gravitational pull.