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
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