Question

The work done by the force of gravity on a satellite moving in a circular orbit around the Earth is:

• A. Positive
• B. Negative
• C. Zero
• D. Infinite

Answer 1

The Correct Option is C

The work done by a force is calculated using the formula:
W = F · d · cos(θ), where:

• W is the work done.
• F is the force applied.
• d is the displacement of the object.
• θ is the angle between the force and the displacement direction.

In the case of a satellite in a circular orbit around the Earth, the gravitational force acts as the centripetal force and always points towards the center of the Earth. The satellite's displacement is tangent to the orbit, making the angle θ = 90°. Thus, the cosine of 90 degrees is 0:
cos(90°) = 0. Therefore, the work done by the gravitational force is calculated as:
W = F · d · cos(90°) = F · d · 0 = 0.
This results in zero work done because the force of gravity is perpendicular to the satellite's motion. Hence, the work done by gravity on the satellite is Zero.