UNIFORM CIRCULAR MOTION An object going in a

UNIFORM CIRCULAR MOTION An object going in a circle at a constant speed. Question: is an object that is undergoing uniform circular motion accelerating?

ROTATION rotation: when an object spins or rotates around an internal axis. Example: A krispy kreme rotating around a straw.

REVOLUTION revolution: when an object turns or revolves around an external axis. Example: A planet revolving around a star. • period: the time • for one revolution Noted as T

LINEAR SPEED linear speed: distance moved per unit of time (speed).

TANGENTIAL SPEED tangential speed (Vt) : the speed of an object that is moving along a circular path. The direction of motion is tangent to the circle. Depends on the circle radius. Larger radius means the speed is greater. Smaller Radius means speed is less

WHICH WILL HAVE THE GREATES T SPEED?

ANGULAR SPEED angular speed (w): the number of rotations per unit of time. Also called rotational speed.

CENTRIPETAL FORCE centripetal force (Fc): any force that will cause an object to take a circular path.

FREQUENCY AND PERIOD Frequency: number of revolutions (turns) per time unit (usually seconds). Noted as f Frequency: number of events (revolutions) time The frequency and period are reciprocals of each other

KEY POINTS FOR UNIFORM CIRCULAR MOTION All points on a rotating rigid object will have the same angular speed (and thus the same angular acceleration). The tangential speed of an object placed on a rotating body will increase as it is moved away from the center of the rigid body. An object that is following a circular path has a net force (Fc) and acceleration (ac) that are acting towards the center of the object.

KEY POINTS CONTINUED Velocity is always tangent to the circle and is always changing. Acceleration goes towards the center of the circle Look at the following rotating disk. Which point has the greater tangential velocity? Which point has the greater angular velocity?

FORMULAS Equations: a c = v t 2 Fc = mac = mvt 2 r r vt = rw w must be in radians per time unit Ac = rw 2 Reminders: 1 revolution = 360 degrees = 2 p rad for one revolution v = d = 2 p r t T