Rotational Motion

Description and Assumptions

This model applies to a rigid body which is executing pure rotation confined to the xy plane about the origin.

Problem Cues

Problems in rotational motion often feature an object which is constrained to rotate about some axle or pivot point. Additionally, the motion of any rigid body which can be treated using the Angular Momentum and External Torque about a Single Axis model can be described as translation of the center of mass plus pure rotation about the center of mass.

Learning Objectives

Students will be assumed to understand this model who can:

• Describe what it means for a system to execute pure rotation.
• Convert from tangential (linear) quantities to the corresponding angular quantities using the radius of the motion.
• Explain the dependence of angular quantities and of tangential quantities describing the motion of a point on the radius of the point from the axis of rotation.
• Define tangential and centripetal acceleration for an object in rotational motion.
• Relate centripetal acceleration to angular velocity.
• Give an expression for the total acceleration of any point in a rigid body executing rotational motion in terms of the angular acceleration of the body, the angular velocity of the body and the radius of the point from the axis of rotation.
• Summarize the analogies between angular motion with constant angular acceleration and linear motion with constant (linear) acceleration.

Model

CompatibleSystems"> Compatible Systems

RelevantInteractions"> Relevant Interactions

RelevantDefinitions"> Relevant Definitions

LawsofChange"> Laws of Change