3.6.1.1
An object in circular motion is always accelerating
Circular Motion — AQA A-Level Physics
- An object in uniform circular motion has a constant linear speed but a continuously changing direction.
- Since velocityThe rate of change of displacement. A vector quantity. Measured in m s⁻¹. is speed in a given direction, the velocityThe rate of change of displacement. A vector quantity. Measured in m s⁻¹. is constantly changing.
- A changing velocityThe rate of change of displacement. A vector quantity. Measured in m s⁻¹. means the object is accelerating, even though its speed is constant.
- This accelerationThe rate of change of velocity. A vector quantity. Measured in m s⁻². is called centripetal accelerationThe rate of change of velocity. A vector quantity. Measured in m s⁻².The accelerationThe rate of change of velocity. A vector quantity. Measured in m s⁻². directed towards the centre of the circular path, required to maintain circular motion. and is directed towards the centre of the circular path.
- The force causing this acceleration is the centripetal forceThe resultant force directed towards the centre of a circular path that causes an object to move in a circle. It is not a separate force but the net force providing circular motion., also directed towards the centre.
Examiner Tips and Tricks
- The linear speed is sometimes called the 'tangential' speed.
- A tangent to a circle is always perpendicular to the radius at that point.
- This means the velocity is perpendicular to the centripetal forceThe resultant force directed towards the centre of a circular path that causes an object to move in a circle. It is not a separate force but the net force providing circular motion. at all times.