Question

The planet earth travels in a circular orbit at constant speed around the sun. What is the net work done on the earth by the gravitational attraction between it and the sun in one complete orbit? Assume that the mass of the earth is given by me

Answer 1

Zero

Step-by-step explanation:

The work done by a force on an object is given by:

`W=Fd cos \theta`

where

F is the magnitude of the force

d is the displacement of the object

`\theta` is the angle between the direction of the force and the displacement

In this problem, the force is the gravitational attraction between the Earth and the Sun, which points always towards the Sun. Therefore, the force is always perpendicular to the displacement of the Earth (which moves tangentially to its circular path). As a result, the angle in the formula is 90 degrees, which means that the cosine part is zero: so, the work done by the gravitational force is always zero, because the force is always perpendicular to the displacement.