Question

mariana races on a BMX bike with 12-in-radius wheels. when she is traveling at a speed of 24 ft/sec, how many revolutions per minute are her wheels making?

Answer 1

First, we have to calculate the circumference of the wheels:

Circumference (c) = pi x 2radius

C = pi x 2(12)

C= 75.4 inches

Convert into feet:

Since 1 ft =12 inches

75.4 in / 12 in/ft = 6.28 ft

Multiply the speed by 60 to convert into ft/min

1minute =60 seconds

24 ft/sec x 60 sec = 1,440 ft/min

Divide the speed by the circumference:

1,440 / 6.28 = 229.3 revolutions per minute