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Circular Motion. Physics 1. What is “circular motion”?. An object that moves in a circular path about an external point is in circular motion. Angular Velocity. An object in circular motion moves with an angular velocity ( w ) expressed in radians per second. Tangential Speed.
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Circular Motion Physics 1
What is “circular motion”? • An object that moves in a circular path about an external point is in circular motion.
Angular Velocity • An object in circular motion moves with an angular velocity (w) expressed in radians per second.
Tangential Speed • At any point in the circular path, the object has a linear (tangential) speed (vT ).
The Value of vT • The tangential speed depends on the size of the path circumference.
The Value of vT • A larger path circumference means a larger path radius (r).
The Value of vT • Tangential speed is directly proportional to the path radius.
The Change in vT • As an object moves between points in a circular path, the direction of vT changes. So, there is a Dv.
The Change in vT • To find the direction of Dv, find the vector sum of v2 – v1. • The change in vT is directed toward the center of the circular path.
The Change in vT • Since there is a change in velocity, the object is undergoing an acceleration toward the center (centripetal). This is called centripetal acceleration (ac ).
The Value of ac • To find the magnitude of ac, use the two triangles formed in the diagram to the right.
The Value of ac • Since the two triangles are similar,
The Value of ac • With vT being uniform in magnitude, s = vT t .
The Value of ac • Rearranging and simplifying,
Centripetal Force • For circular motion, the net force influencing acceleration is called a centripetal force (Fc ).
Centripetal Force • Using Newton’s Second Law equation (Fnet = ma),