5.5 Rotational Equilibrium and Newton’s First Law in Rotational Form

Describe the conditions under which a system’s angular velocity remains constant.

• A system may exhibit rotational equilibrium (constant angular velocity) without being in translational equilibrium, and vice versa.
  • i. Free-body and force diagrams describe the nature of the forces and torques exerted on an object or rigid system.
  • ii. Rotational equilibrium is a configuration of torques such that the net torque exerted on the system is zero. Relevant equation:
  • iii. The rotational analog of Newton’s first law is that a system will have a constant angular velocity only if the net torque exerted on the system is zero.
• A rotational corollary to Newton’s second law states that if the torques exerted on a rigid system are not balanced, the system’s angular velocity must be changing. BOUNDARY STATEMENT AP Physics 1 does not expect students to simultaneously analyze rotation in multiple planes. | TOPIC 5.6 Newton’s Second Law in Rotational Form