Free AP Physics C lesson

Rotational Dynamics

This AP Physics C: Mechanics lesson is designed for AP Physics C self-study. It includes 3 video lessons, 6 practice questions, and an estimated completion time of 24 minutes.

Video lessons

  1. Rotational Dynamics (Newton's Second Law in Rotational Motion)

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  2. Rotational Dynamics (part 2)

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  3. Rotational Dynamics (part 3)

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Practice covered

  1. Newton's second law for rotational motion states that angular acceleration (alpha) equals the net torque divided by which quantity?
  2. A uniform cylinder of mass 2 kg and radius 1 m has a string wrapped around it. The string is pulled with a force of 10 N tangent to the cylinder's edge. Calculate the angular acceleration (in rad/s^2) of the cylinder. The rotational inertia of a cylinder is I = 1 / 2MR^2.
  3. A solid sphere rolls down an inclined plane without slipping. Which force provides the torque that causes the sphere to rotate?
  4. A solid sphere with rotational inertia I = 2 / 5MR^2 rolls down an incline at angle theta = 30°. What is the linear acceleration of its center of mass (in terms of g)? Express your answer as a decimal coefficient times g (e.g., if a = 0.5g, enter 0.5).
  5. A solid cylinder of mass M and radius R is mounted on a frictionless axle. A bucket of mass M hangs from a string wrapped around the cylinder. When released, why is the tension in the string less than Mg?
  6. A cylinder with rotational inertia I = 1 / 2MR^2 and mass M is connected to a hanging bucket of mass M via a string. When released, what is the acceleration of the bucket (in terms of g)? Express your answer as a decimal coefficient times g (e.g., if a = 0.5g, enter 0.667).
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