1. Circular Motion

2. Rotation and Revolution
What is an axis?
The straight line around which a rotation takes place

3. Rotation and Revolution
When the object turns around an internal axis (the axis is located within the body of the object)…
the motion is called rotation

4. Rotation and Revolution
When an object turns around an external axis….
the motion is called a revolution

5. Rotation and Revolution Review

6. Review The Earth ______ around the sun once every ____.
around an axis (through it’s poles) once every _____.
Revolves
days
Rotates
24 hours

7. Please define the following vocabulary words
1) axis ) center of gravity
2) centrifugal force ) center of mass
3) centripetal force
4) linear speed
5) revolution
6) rotation
7) rotational speed
8) tangential speed
Vocab quiz Thursday

8. Review
1) Match the following terms: Orbit Revolve Spin Rotate 2) Which object rotates and which revolves? Top? Moon?
Orbit → Revolve
Spin → Rotate
Rotates Revolves

9. Review
Is it correct or incorrect to say that the Earth is rotating around the Sun? Why?

10. Rotational Speed
Which moves faster, the outer horse on a merry go round or the inner horse?

11. Rotational Speed 2 parts 1) Linear Speed = Distance Time
2) Rotational Speed= Rotations

12. Review
At the center of the axis, do you have linear or rotational speed?
Rotational

13. Review
As you move outward do you increase your linear or rotational speed?
Linear

14. Review
1) Which part of the Earth’s surface has the greatest rotational speed? Linear speed?
All parts have the same rotational speed
The equator has the greatest linear speed

15. 2) Trains ride on a pair of tracks
2) Trains ride on a pair of tracks. When traveling in a straight line, the tracks are the same length. But which track is longer for a curve, the one on the outside on the one on the inside curve?

16. Summary
In a rigid rotating system, all parts have the same (rotational, linear) speed, but the
(rotational, linear) speed varies.
rotational, linear
Linear speed depends on the _____ from the axis of rotation and on the _____ speed.
distance, rotational