Peoples Physics Book Version-3

9.1. The Big Idea http://www.ck12.org

MEDIA

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MEDIA

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Key Equations

d=rθ

the path length along an arc is equal to the radius of the arc times the angle through which the arc passes

v=rω

the linear velocity of an object in rotational motion that is not sliding on surface or slipping with respect to a rope is
the radius of rotation times the angular velocity

MEDIA

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a=rα

the linear acceleration of an object in rotational motion that is not sliding on surface or slipping with respect to a
rope is the radius of rotation times the angular acceleration; this isinthe direction of motion

ac=−v^2 /r=−rω^2

the centripetal acceleration of an object in rotational motion depends on the radius of rotation and the angular speed;
the sign reminds us that it points inward towards the center of the circle; this is justmv^2 /rfrom centripetal motion.