# The wheels of a car have a radius 11 in and arc rotating at 1500rpm. How do you find the speed of the car in mi/h?

May 28, 2018

The speed of the car was $98.17$ miles/hour

#### Explanation:

$r = 11$ inches , revolution $= 1500$ per minute

In $1$ revolution the car advances $2 \cdot \pi \cdot r$ inches

$r = 11 \therefore 2 \pi r = 22 \pi$ inches .

In $1500$ revolution/minute the car advances $22 \cdot 1500 \cdot \pi$

inches $= \frac{22 \cdot 1500 \cdot \pi \cdot 60}{12 \cdot 3 \cdot 1760} \approx 98.17 \left(2 \mathrm{dp}\right)$mile/hour

The speed of the car was $98.17$ miles/hour [Ans]