Question

A car is moving at the rate of 80km/h. the diameter of its wheel is 60cm. a, find the number of revolutions per minute that the wheels are rotating. b, find the angular speed of the wheels in radians per second.

Answer 1

60 cm = .6 m
one rotation = .6π m

80 km/h = 80,000 m/60 min = 400/3 m/min
number of rotations/min
= (400/3) / (.6π)
= 70.7 rotations in a minute

or 70.7/60 rotations per minute
= 1.1789 rotations per second

but 1 rotation = 2π radians,
so the angular velocity = 2π(1.1789..) radians/sec
= appr 7.4 radians/sec

check my arithmetic