Circular Motion

Question 1

What is a radian?

Answer 1

1 rad is the angle subtended from (made by) an arc that has a length equal to the radius.

Question 2

What is tangential speed?

Answer 2

The tangential speed (v) of a particle is its linear speed tangential to the circle.

Question 3

What is linear speed?

Answer 3

The linear speed (v) of a particle is the distance travelled with respect to time. Measured in m/s

Question 4

What is angular velocity?

Answer 4

The angular velocity (ω) is the rate of change of angle with time. Measured in rad/s

Question 5

What is period or periodic time?

Answer 5

Denoted by T, it is the time taken for one complete revolution of a circle.

Question 6

What is centripetal force?

Answer 6

The force directed towards the centre of a circle that is necessary to keep a body moving in a circular path. It is denoted by F

Question 7

State the factors affecting centripetal force.

Answer 7

Greater force is required when:
- The object is moving with greater velocity
- The object has a smaller radius to turn
- The object has a higher mass

Question 8

What is centripetal acceleration?

Answer 8

Denoted by a, it is the acceleration towards the centre of a body in orbit.

Question 9

What is geostationary orbit?

Answer 9

If a satellite is to be in geostationary orbit, then it has to stay above the same point on Earth at all times.

Question 10

What are the three conditions necessary for geostationary orbit?

Answer 10

• The satellite is on the equatorial plane
• The period of orbit is 24 hours
• The satellite moves in the same direction as the Earth