5.2 Circular Motion

Question 1

Define angular velocity

Answer 1

The rate of change of angle of an object moving in a circular path

Question 2

Define centripetal force

Answer 2

The resultant force towards the centre of a circle

Question 3

Define centripetal acceleration

Answer 3

Acceleration towards the centre of a circle that causes the resultant centripetal force

Question 4

How are centripetal force and velocity related? (2)

Answer 4

Centripetal force always acts perpendicular to velocity

There is no component of force in the direction of motion so the speed remains constant

Question 5

Why are objects in circular motion accelerating if they have constant speed?

Answer 5

The direction is constantly changing so their velocity is changing, meaning they have acceleration

Question 6

How is linear velocity related to radius?

Answer 6

For any object with constant angular velocity, linear velocity is directly proportional to the radius

Question 7

How can circular motion be investigated using a bung? (2)

Answer 7

Use a bung attached to a weight using a piece of string

Swing the bung in a horizontal circle so that the suspended weight stays stationary; mg = centripetal force

Question 8

Motion in a vertical circle (3)

Answer 8

Centripetal force is constant at all points
At top of circle, centripetal force = tension + weight
At bottom of circle, centripetal force = tension - weight