Circular motion
|
The force that pulls an object out of a straight line path into a circular orbit is called the centripetal force. (The word means centre seeking). It is the force on the orbiting object. |
Angular velocity
When an object is travelling in a circle it has an instantaneous linear velocity but it also has an angular velocity (
w).
This is defined as the rate of change of angle with time and is usually expressed in radians per second.
Period of the motion (T) = circumference/linear velocity =2pr/v
= total angle /angular velocity = 2p/w |
Since T is the period (the time to make one complete rotation) the number of rotations per second (n) is 1/T and is the frequency of the motion.
|
Linear velocity and angular velocity: v = rw |
When an object moves in a circle the linear velocity must be constantly changing as the direction of motion is changing - there must therefore be an acceleration - the centripetal acceleration, and therefore a force - the centripetal force.
Both the centripetal acceleration and the centripetal force are directed towards the centre of the circle.
