8.1.3 - Orbital Motion, Natural & Artificial Satellites

What allows planets and satellites to maintain circular orbits?

• Gravity provides the gravitational force that acts as the object’s centripetal force.

• The presence of a centripetal force allows for the object to maintain its circular orbit.

What type of satellite can a planet’s moon be described as?

A natural satellite.

Give two examples of artificial satellites.

1. TV satellites.

2. Satellites used for satellite imaging.

Explain why for a stable orbit, the radius of orbit must change if the speed changes.

• At higher speeds, the object requires a greater centripetal force.

• For a greater centripetal force, the gravitational force must increase.

• This is achieved by the radius of the orbit being reduced.

Explain how the force of gravity acting on a satellite affects its speed and velocity.

• The force can alter its velocity since the direction is continually changing.

• It can’t cause a change of speed since there is no force component in the direction of motion.