Angular velocity and centripetal acceleration physics question?

A car is travelling with a constant speed of 23.4 m/s. The car is equipped with 205/65 R15 tires that have radius equal to 0.325 m. Find the angular velocity and the centripetal acceleration of a small stone logded in the thread of one of the tires. How many times larger is that centripetal acceleration compared to the acceleration due to gravity?

V = Rw
=>Angular velocity w = V/R = 23.4/ 0.325 = 72 rad/s

centripetal acceleration alpha = R w^2
= 0.325 * 72^2
= 1685 rad/ss
As compared to g it is 1685/ 10 times larger.

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