Review

1
Review

• Pendula, Centripetal Force, Gravity

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• Concepts
• Pendular motion is independent of mass and the
  displacement (for small values)
• Pendular motion depends on the length of the
  string and the acceleration of gravity
• Centripetal force is the force needed to prevent
  an object from following its natural tendency (a
  straight line due to inertia) and make it follow
  a closed curve (circle or ellipse)
• Centripetal force and centripetal acceleration
  always point to the center of the circle
• Gravity is an attractive force depending on the
  product of the masses
• And on the inverse square of the distance between
  the center of mass

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• Equations
• Pendulum
• Centripetal force
• Gravity

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• Sample Problems
• Pendulum
• (1) Given a 2m string, what is the period of a
  pendulum?
• (2) Given a 3m string and a period of 10sec, what
  it the local acceleration due to gravity?
• Centripetal force
• (1) What is the centripetal force required to
  keep a 1000kg car on a circular track with radius
  100m with a speed of 10m/sec?
• (2) What is the centripetal force required to
  keep the moon in its orbit?
• (3) How does that compare to the gravitational
  attraction between the Earth and the Moon?
• Gravity
• (1) What is the force of gravity between the
  Earth and the Sun?
• (2) Given the mass of the Earth and the radius of
  the Earth, calculate g.

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Answer to pendulum problem one