Kristyna Partain, Chris Engler, Risa Thompson, Stuart Goldberg 3B-Physics

In physics, another form of measurement is used to describe fractions of revolutions. The radian is defined as ½ of a revolution. The Greek letter theta,,is used to represent the angle of revolution. As an object rotates, the change in the angle is called angular displacement.

Angular Velocity The angular velocity of an object is angular displacement divided by the time taken to make the displacement. Angular Velocity of an Object w = ∆ divided by ∆t The angular velocity is equal to the angular displacement divided by the time required to make the rotation.

Angular Acceleration Angular Acceleration is the change in angular velocity divided by the time required to make the change. If the change in angular velocity is positive, then the angular acceleration is also positive. Angular acceleration of an object = ∆w divided by ∆t

QuantityLinearAngularRelationship Displacement Velocity Acceleration d (m) v (m/s) a (m/s 2 ) (rad) w (rad/s) (rad/s 2) d = r v = rw a = r

Angular Displacement As an angle rotates, the change in the angle is called angular displacement.

Rotational Dynamics Key Concepts When torque is exerted on an object, its angular velocity changes. Torque depends on the magnitude of the force, the distance from the axis of rotation at which it is applied, and the angle between the force and the radius from the axis of rotation to the point where the force is applied. Newton’s Second Law for rotational motion states that angular acceleration is directly proportional to the net torque and inversely proportional to the moment of inertia.

Your bicycle tire represents rotational motion.

Propellers represent rotational motion.

Examples of Rotational Motion The solar system represent rotational motion.