Rotational Motion Rapid Review for AP Physics C

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By — McGraw-Hill Professional
Updated on Feb 11, 2011

For a more thorough review, refer to these concepts:

Rapid Review

  • Rotational kinematics is very similar to linear kinematics. But instead of linear velocity, you work with angular velocity (in radians/s); instead of linear acceleration, you work with angular acceleration (in radians/s2); and instead of linear displacement, you work with angular displacement (in radians).
  • Always work in radians, not degrees.
  • Moment of inertia is the rotational equivalent of mass—it's a measure of how difficult it is to start or stop an object spinning.
  • The rotational equivalent of Newton's second law says that the NET torque on an object equals that object's moment of inertia multiplied by its angular acceleration.
  • To solve problems involving a massive pulley, make sure you draw a free-body diagram of the pulley. Also, when a rope passes over a massive pulley, the tension in the rope on one side of the pulley won't be the same as the tension on the other side.
  • The total kinetic energy of a rolling object is equal to the sum of its linear kinetic energy and its rotational kinetic energy.
  • Angular momentum in a closed system is conserved. An object doesn't necessarily need to travel in a circle to have angular momentum.
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