point of circumference?

Question

A tire has a radius of 12 cm. if the tire is rotating at a constant angular speed of 30 revolutions per second, then the tagential velocity of a point on the circumference is??

a) 31.51
b) 3.08
c)22.62
d)12.55
e) 5.13

please help/explain thanks!!!

Answer 1

v = rw, where v is tangential velocity, r is radius, and w is angular velocity expressed in radians/sec. 1 revolution is 2*pi radians, so 30 rev/s is 30*2*pi = 188 rad/s.

v = rw = (12 cm)(188 rad/s) = 2262 cm/s

If the units of your answers are m/s, then 2262 cm/s = 22.62 m/s, and c) is your answer.