A computerized spin machine rotates a 25 inch diameter tire at 480 revolutions per minute

Question

A. Find the road speed (in miles per hour) at which the tire is being balanced.

b. At what rate should the spin balance machine be set so that the tire is being tested for 55 miles per hour?

Answer 1

A. v = ωr = 480·2π/60·3600·12.5·1.5783·10^-5mi/h = 35.7 mi/h

B.n/480 = 55/35.7; n = 739.5 revolutions per minute.