CIE A Level Physics (9702) 2019-2021

Revision Notes

14.2.1 Centripetal Acceleration

What Causes Centripetal Acceleration?

  • Velocity and acceleration  are both vector  quantities
  • An object in uniform circular motion is continuously changing direction, and therefore is constantly changing velocity
    • The object must therefore be accelerating
  • This is called the centripetal acceleration and is perpendicular to the direction of the linear speed
    • Centripetal means it acts towards the centre of the circular path


Force and acceleration direction, downloadable AS & A Level Physics revision notes

Centripetal force and acceleration are always directed towards the centre of the circle

  • The centripetal acceleration is caused by a centripetal force of constant magnitude that also acts perpendicular to the direction of motion (towards the centre)
  • Therefore, the centripetal acceleration and force act in the same direction

Exam Tip

  • The linear speed is sometimes referred to as the ‘tangential’ speed
  • A tangent is a straight line which touches a circle or curve at exactly one point
  • The key feature of a tangent of a circle is that it always acts perpendicular to its radius
  • You can find out more in the A Level Maths revision notes on Tangents

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