Causes of Circular Motion

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Causes ofCircular Motion

• Students will
• calculate the force that maintains circular
  motion
• explain fictitious forces and
• apply Newtons universal law of gravitation to
  find the gravitational force between two masses.

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Causes ofCircular Motion
When a ball is whirled in a circle, a force
directed toward the center of the balls circular
path acts on it.
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Causes ofCircular Motion
The force that maintains circular motion is Fc.
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Force that Maintains Circular Motion
Sample Problem 7H (p 261) A pilot is flying a
small plane at 30.0 m/s in a circular path with
a radius of 100.0 m. If a force of 635 N is
needed to maintain the pilots circular motion,
what is the pilots mass?
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Force that Maintains Circular Motion
Sample Problem 7H (p261)Givenvt 30.0 m/sr
100.0 mFc 635 N Unknown m ?
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Force that Maintains Circular Motion
Sample Problem 7H (p261)
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Assignment Practice 7H (p261) (15 min)
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• Assignment Practice 7H (p261) (15 min)
• m 30.0 kg
• m 86.5 kg
• m 18.5 kg
• vt 87.7 m/s

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Newtons Law of Universal Gravitation

• Gravitational Force
• the mutual force of attraction between particles
  of matter.

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Newtons Law of Universal Gravitation

• Gravitational Force depends on the distance
  between the two masses.

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Newtons Law of Universal Gravitation
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Newtons Law of Universal Gravitation
Sample Problem 7I (p 264) Find the distance
between a 0.300 kg billiard ball and a 0.400 kg
billiard ball if the magnitude of the
gravitational force is 8.92 10-11 N.
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Newtons Law of Universal Gravitation
Sample Problem 7I (p 264)Givenm1 0.300 kgm2
0.400 kgFg 8.9210-11 N Unknown r ?
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Newtons Law of Universal Gravitation
Sample Problem 7I (p 264)
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Assignment Practice 7I (p265) (25 min)
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• Assignment Practice 7I (p265) (25 min)
• r 0.331 m
• r 9.4106 m
• 664 N
• 243 N
• 14000 N

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Homework

• Complete Worksheet 7-3Causes of Circular
  Motion
• Section Review (page 265 1-5)