A pick-up truck is fitted with new tires which have a diameter of 42 inches. How fast will the pick-up truck be moving when the wheels are rotating at 280 revolutions per minute? Express the answer in miles per hour rounded to the nearest whole number.

Respuesta :

280 revolutions per minute is:
280/60 = 4,66667 revolutions per second.

now we need to calculate perimeter of the tire
O = D*pi = 42*3,1415 = 131.943 inches

Speed of truck is:
V = 4,66667 * 131.943 = 615.73 inches per second.

Now we need to express this in miles per hour.
615,73 * 1,5782*10^(-5) *3600

V = 34.984 miles per hour.

after rounding we get
V = 35 miles per hour.