AQA A Level Physics复习笔记6.1.1 Circular Motion

• Velocity and acceleration are both vector quantities
• An object in uniform circular motion has a constant linear speed
• However, it is continuously changing direction. Since velocity is the speed in a given direction, it, therefore, has a constantly changing velocity
  • The object therefore must be accelerating
  • This is because acceleration is defined as the rate of change of velocity

   

• This acceleration 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)
  • This is a result of Newton's Second Law

   

• Therefore, the centripetal acceleration and force act in the same direction