# Why does a satellite in a circular orbit travel at a constant speed? a) There is no component of...

## Question:

Why does a satellite in a circular orbit travel at a constant speed?

a) There is no component of force acting along the direction of motion of the satellite.

b) The net force acting on the satellite is zero.

c) There is a force acting opposite to the direction of the motion of the satellite.

d) The gravitational force acting on the satellite is balanced by the centrifugal force acting on the satellite.

## Satellite motion:

The satellite revolves around the planet in the circular orbit. The force exerts on the object in the circular motion is known as the centrifugal force. This force is directly proportional to the square of the velocity of the motion.

The satellite revolves around the planet, therefore, the required centrifugal force is provided by the gravitational force between the satellite and the planet.

The expression of the gravitational force is given by

{eq}\rm F = \dfrac{GMm}{r^{2}} {/eq}

where

• M is the mass of the planet
• m is the mass of the satellite
• r is the radius of the orbit

Since the gravitational force remains constant, in the circular orbit, therefore the velocity of the satellite remains constant.

Hence the correct option is "d"