# 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

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

### Author: Katie

Katie has always been passionate about the sciences, and completed a degree in Astrophysics at Sheffield University. She decided that she wanted to inspire other young people, so moved to Bristol to complete a PGCE in Secondary Science. She particularly loves creating fun and absorbing materials to help students achieve their exam potential.
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