the wheels of a car are rotating at 840 revolutions per minute. If the car is traveling at 55 miles per hour, find the diameter of the wheels in feet.
2006-09-17 16:59:58 · 6 answers · asked by Amy 1 in Science & Mathematics ➔ Mathematics
speed of the car=2*pi*r*n
2*3.14*r*840/60=55*17.6
r=11 inch
diameter=22/12=1.83 foot
2006-09-17 17:07:37 · answer #1 · answered by raj 7 · 0⤊ 0⤋
The solution is simple.
First, calculate how many miles is the car traveling per minute.
55 miles per hour = 11/12 miles per minute
Convert that number to feet per minute.
11/12 miles per minute = 4840 feet
Then, divide that by 840 (the rotations of the wheel per minute).
4840 feet / 840 = 5.7619 feet
There you have the circumference of the wheel. Why? Because it took 840 rotations of the wheel to get the car that far in a minute.
For example, say you were on a bike, and one full rotation of your bike wheel brings you forward 3 feet. That would mean that the circumference of the bike wheel is 3 feet. Now, if your bike wheel rotated 60 times per minute, you'd be traveling 3*60=180 feet per minute!
Continuing on with the problem:
Then, plug the circumference of the wheel into the formula circumference. Solve for diameter.
circumference = pi * diameter
5.761 feet = 3.14159 * diameter
diameter = 1.83378 feet
There you have your answer! :)
2006-09-17 17:06:54 · answer #2 · answered by Tim H 2 · 0⤊ 0⤋
try 840 times 55
2006-09-17 17:18:25 · answer #3 · answered by sunflare63 7 · 0⤊ 0⤋
The answer is 0,11 feet
55 miles=290,4 feet
840* 2*pi*r=290,4
r=290,4/ (1680 *pi)
=290,4/5275,2
r=0,055 feet
diameter=2r= 0,11 feet
2006-09-17 17:10:13 · answer #4 · answered by iyiogrenci 6 · 0⤊ 0⤋
It seems that not enough information is given. What is the distance travelled?
2006-09-17 17:10:22 · answer #5 · answered by Liwayway 3 · 0⤊ 0⤋
2.5 feet.
2006-09-17 17:07:04 · answer #6 · answered by Anonymous · 0⤊ 0⤋