triginomitry car

Question

A car is moving at a rate of 70 miles per hour, and the diameter of its wheels is 1.8 feet. 

Find the number of revolutions per minute the wheels are rotating.

Find the angular speed of the wheels in radians per minute.

Answer 1

70mph=5280(70)/60= 7(5280)/6=7(880)=6,160 ft/min

=102.667 ft/s

radius =1.8/2 =0.9 ft

circumference= pir^2= .81pi

rpm= 6160/.81pi = about 2,420.73 revolutions per minute

angular speed in radians per minute = rpm x 2pi =

6160(2pi)/.81pi=12,320/.81=15,209.87 rad/min