A particle of mass *m* moves with constant speed *v* on a circular path of radius *r*. Find the magnitude of average force on it in half revolution.

Change in momentum = Final momentum - initial momentum

= mv - (-mv) = 2mv

Average force = Change in momentum/ time taken

time taken = distance/ speed = πr/v

Average force = 2mv/ (πr/v) = 2mv^{2}/(πr)

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