Circular Motion 3'8 in the text book

1
Circular Motion ( 3.8 in the text book) Angular
distance
r
s
(or degrees or revolutions)
?
s r ?
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2
Circular Motion ( 3.8 in the text book) Angular
distance
v
r
s
(or degrees or revolutions)
?
?
s r ? ? ??/?t v r ?
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3
Uniform Circular Motion ( 3.8 in the text book)
There is an acceleration because the velocity is
changing direction.
Uniform means constant v
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4
Question

• For uniform circular motion, the acceleration
• is parallel to the velocity.
• is directed toward the center of the circle.
• is larger for a larger orbit at the same speed.
• is always due to gravity.
• is always negative.

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Answer

• For uniform circular motion, the acceleration
• is directed toward the center of the circle.

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Checking Understanding
When a ball on the end of a string is swung in a
vertical circle

• We know that the ball is accelerating because
• the speed is changing.
• the direction is changing.
• the speed and the direction are changing.

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7
Answer
When a ball on the end of a string is swung in a
vertical circle

• We know that the ball is accelerating because
• the direction is changing.

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Checking Understanding
When a ball on the end of a string is swung in a
vertical circle

• What is the direction of the acceleration of the
  ball?
• Tangent to the circle, in the direction of the
  balls motion
• Toward the center of the circle

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9
Answer
When a ball on the end of a string is swung in a
vertical circle

• What is the direction of the acceleration of the
  ball?
• Toward the center of the circle

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Uniform Circular Motion
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11

• A coin sits on a rotating turntable.
• At the time shown in the figure, which arrow
  gives the direction of the coins velocity?

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12
Answer

• A coin sits on a rotating turntable.
• At the time shown in the figure, which arrow
  gives the direction of the coins velocity?

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