If a wheel with a radius of 70 inches spins at a rate of 600 revolutions per minute, find the approximate linear velocity in miles per hour.

This is the concept of speed:

ω=600 rev/min=600*2π rad/min=1200 rad/min

v=rω=70*1200π = 84,000 in/min

converting the above in miles per hour we get:

84000 in/min

= (84000*1.6*10^ (-5) * 60)

=80.64 mph