Solve the problem
-Each tire of an automobile has a radius of $2.5$ feet. How many revolutions per minute (rpm) does a tire make when the automobile is traveling at a speed of 115 feet per sec? Round your answer to the nearest tenth.
A) $439.3 \mathrm { rpm }$
B) $2745.4 \mathrm { rpm }$
C) $7.3 \mathrm { rpm }$
D) $878.5 \mathrm { rpm }$

Question

Quizplus · Accepted Answer

The circumference of a tire is given by $C = 2\pi r$, where $r$ is the radius. For a radius of $2.5$ feet, the circumference is $2\pi(2.5) = 5\pi$ feet. To find the revolutions per minute, we first convert the speed from feet per second to feet per minute by multiplying by $60$ (since there are $60$ seconds in a minute), giving $115 \times 60 = 6900$ feet per minute. The number of revolutions per minute is then the distance traveled in one minute divided by the circumference of the tire, or $6900 / (5\pi) \approx 439.3$ rpm.

Solve the Problem -Each Tire of an Automobile Has a Radius

Solve the Problem
-Each Tire of an Automobile Has a Radius