Question

A tire on sal's car makes 13 revolutions per second while traveling down the freeway. sal's tires are 2 ft in diameter, and there are 5,280 feet in 1 mile. how far does sal drive in 1 hour? round the answer to the nearest mile. a. 28 miles b. 56 miles c. 60 miles d. 111 miles

Answer 1

Compute the speed of the car:

$\dfrac{2\pi\,\rm ft}{1\,\rm rev} \cdot \dfrac{13\,\rm rev}{1\,\rm s} \cdot \dfrac{1\,\rm mi}{5280\,\rm ft} \cdot \dfrac{3600\,\rm s}{1\,\rm h} = \dfrac{195\pi}{11} \dfrac{\rm mi}{\rm h} \approx 55.6919 \dfrac{\rm mi}{\rm h}$

So after 1 hour, Sal will have driven about 56 mi.