4.__Uniform Circular
Motion and Force
__

Apply
Newton’s 2nd Law along
the radial direction (directed
toward the center):

example: A hockey puck of mass m moving in a circular path of radius R on a horizontal frictionless surface.

For an object of mass *m* to move
in a circle of radius *R* with a constant speed *v*, there must be a net centripetal force (mass × centripetal acceleration) with the magnitude *m
v**2**/R* and
directed along the radius toward the centre of the circle. In the example above the tension *T*
provide the centripetal force necessary to keep the object in circular motion.