What is AP Physics 1 Unit 5 about?
Unit 5 Torque and Rotational Dynamics is a current AP Physics 1 unit with an official multiple-choice weighting of 10–15%. This hub maps every topic in the unit to focused lessons, examples, representations and practice.
- Official unit weighting: 10–15% of the MCQ section.
- Every official topic in this unit has its own lesson and 42-MCQ/4-FRQ practice bank.
- Use the unit hub for sequencing; use the child topic pages for exact definitions and worked reasoning.
Unit 5 · Torque and Rotational Dynamics
Unit 5 extends kinematics and Newton’s laws to rotating rigid systems through angular variables, torque, and rotational inertia.
Unit 5 topic map
Use the unit hub to understand how the ideas connect; use each topic lesson for definitions, real examples, equations, worked reasoning, misconceptions and focused practice.
Rotational Kinematics
Rotational kinematics describes how angular position, angular velocity, and angular acceleration change as an object rotates about an axis.
Connecting Linear and Rotational Motion
For a rigid object rotating about an axis, angular motion determines the linear tangential motion of points through their distance from the axis.
Torque
Torque measures the rotational effect of a force about a chosen axis and depends on force magnitude, distance from the axis, and the perpendicular geometry of the force.
Rotational Inertia
Rotational inertia (moment of inertia) measures how strongly a mass distribution resists angular acceleration about a specified axis; it depends on both total mass and how far that mass lies from the axis.
Rotational Equilibrium and Newton’s First Law in Rotational Form
Rotational equilibrium occurs when net torque about an axis is zero, so angular velocity does not change; an object can be at rest or rotate at constant angular velocity.
Newton’s Second Law in Rotational Form
Newton’s second law for rotation states that the net external torque on a rigid system equals its rotational inertia times angular acceleration.