Circular Motion

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

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 http://www.youtube.com/watch?v=9LzZ1ORjSjk

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

Rotation and Revolution Review

Review The Earth ______ around the sun once every ____. around an axis (through it’s poles) once every _____. Revolves 365.25 days Rotates 24 hours

Please define the following vocabulary words 1) axis 9) center of gravity 2) centrifugal force 10) center of mass 3) centripetal force 4) linear speed 5) revolution 6) rotation 7) rotational speed 8) tangential speed Vocab quiz Thursday

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

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

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

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

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

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

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

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?

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