S1.4 Application: circular motion
[A] Uniform circular motion
Key Point 1.8
A particle moving in a circle of radius r at uniform speed v has an acceleration of magnitude v2/r, directed towards the centre of the circle (centripetal).Commentary
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Commentary
- speed is constant
- but direction is changing
- so velocity is changing
- so there is an acceleration
- it is a vector
- we need to find its magnitude and its direction
[B] Generalisations
- If the path is not circular: the result holds at each point on the path, with r the radius of curvature at that point.
- If the speed is not constant: there is also a component of acceleration of magnitude
tangential to the path.

Commentary
Learning Resources
![]() | HRW Chapter 4.7 |
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