What is an axis?

The straight line around which a rotation takes place

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

When an object turns around an external axis….

the motion is called a revolution

The Earth ______ around the sun once every ____.

The Earth _____ around an axis

(through it’s poles) once every _____.

Revolves

365.25 days

Rotates

24 hours

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

1) Match the following terms:

Orbit Revolve

Spin Rotate

2) Which object rotates

and which revolves? Top? Moon?

Orbit → Revolve

Spin → Rotate

Rotates Revolves

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

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

2 parts

1) Linear Speed = Distance

Time

2) Rotational Speed=

Rotations

Time

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

Rotational

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

Linear

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

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