1. Centripetal Acceleration The force on required to make an object move in a circle is always directed towards the centre of the circle, so the object must always be accelerating towards the centre of the circle. This acceleration is called the ‘centripetal acceleration’. EG Bung on a string : Direction of rotation Force and acceleration

2. r r  It starts at point A with velocity v 1... And finishes at B with velocity v 2... Having moved through an angle . Remember definition of radian: v1v1 A v2v2 B But arc AB is also the distance travelled in time  t at speed v.  arc AB = v  t Consider a small section of the bung’s motion:

3. Since v 1 and v 2 are both tangents, the angle between them is . For small angles Now consider the velocity vector diagram. v1v1 v2v2 vv Add starting velocity & change in velocity ‘tip to tail’ to obtain new velocity.  From page above:So:

4. Questions page 25 1. a. b. 2. a. b. 3. a. b.If the satellite is in orbit, then its centripetal acceleration is equal to the acceleration of free fall on the planet it is orbiting

5. 4. a. b. c.

6. Centripetal Acceleration The force on required to make an object move in a circle is always, so the object must always. This acceleration is called the EG Bung on a string : Direction of rotation

7. r r  It starts at point A with velocity v 1... And finishes at B with velocity v 2... Having moved through an angle . Remember definition of radian: v1v1 A v2v2 B But arc AB is also the distance travelled in time  t at speed v. Consider a small section of the bung’s motion:

8. Since v 1 and v 2 are both tangents, the angle between them is . For small angles Now consider the velocity vector diagram. v1v1 v2v2 vv Add starting velocity & change in velocity ‘tip to tail’ to obtain new velocity.  From page above:

9. Questions page 25