A bicyclist's wheel is traveling at 250 revolutions per minute. If the bicycle tire has a diameter of 29 inches, what is the bicyclist's speed in miles per hour?
I got 43.14 mph. Let me know if that seems right.
250 rot/min x pi x 2r = distance / min
250 x pi x 2 x 29 = 45553.093 in/min
in/min x 60 min/hr x 1 ft/ 12 in x 1mi/5280ft = 43.137 m/hr
Wait a minute!! The diameter is 29 inches, not the radius.
250 * 29π inches / 1 minute
= 7250π inches / 1 minute
= 7250π inches / (1/60 hours)
= (7250π / 63360 miles) / (1/60 hours)
= 7250π / 1056 miles per hour
≈ 21.569 miles per hour