Did this video help you?
Circular Motion (Cambridge O Level Physics)
Revision Note
Circular Motion
- Velocity is a vector quantity, and the velocity of an object is its speed in a given direction
- When an object travels along a circular path, its velocity is always changing
- The speed of the object moving in a circle might be constant - that is, it is travelling the same distance every second
- However, the direction of travel is always changing as the object moves along the circular path
- This means that an object moving in circular motion travels at a constant speed but has a changing velocity
- The image below shows an example of a famous object that moves in a circular path with a constant speed but changing direction:
International Space Station Orbiting Earth
The International Space Station’s velocity is always changing - it whizzes around the Earth at a constant speed of about 7660 m/s but is always changing direction
- When a force acts at 90 degrees to an object’s direction of travel, the force will cause that object to change direction
An Impact Force Causing a Change in the Motion of a Car
When the two cars collide, the first car changes its direction in the direction of the force
- If the force continues to act at 90 degrees to the motion, the object will keep changing its direction (whilst remaining at a constant speed) and travel in a circle
- This is what happens when a planet orbits a star (or satellite orbits a planet)
The Moon Orbiting the Earth
The Moon is pulled towards the Earth (at 90 degrees to its direction of travel). This causes it to travel in a circular path
- The force needed to make something follow a circular path depends on a number of factors:
- The mass of the object
- A greater mass requires a greater force when the speed and radius are constant
- The speed of the object
- A faster-moving object requires a greater force when the mass and radius are constant
- The radius of the circle
- A smaller radius requires a greater force to keep the speed and radius constant
- The mass of the object
You've read 0 of your 10 free revision notes
Unlock more, it's free!
Did this page help you?