Question

A motorized scooter has tires with a radius of 3 1/2 inches.vThe tires make one revolution every 1/10 second. Find the speed of the scooter in miles per hour. (hint: THe speed of an object spinning in a circle is equal to the circumference divided by the time it takes to complete one revolution)

Answer 1

Hello @stylestar5678 and Welcome to OpenStudy :)
first find the circumference of the tire
cricumference = 2*pi*r = ?

Answer 2

then know that there are 63360 inches in one mile
and that there are 3600 seconds in one hour

Answer 3

im a bit confused on how to solve it and put it all together

Answer 4

that's ok, first find the circumference
can you do that? :)

Answer 5

how?

Answer 6

circumference = 2*pi*r = 2*(pi)*(3.5inches) = ?

Answer 7

so its about 21.98?

Answer 8

is it?

Answer 9

21.99 yes :)

Answer 10

now what?

Answer 11

so now you have the tires spinning at the speed of
21.99 inches
------------
0.1 secs

do you see where I got those numbers? :)

Answer 12

yes

Answer 13

now we want to get those inches to become miles
and those seconds to become hours

Answer 14

proportions?

Answer 15

21.99 inches 1 mile 3600 secs
------------ x ------------ x ---------
0.1 secs 63360 inches 1 hour

this would get the seconds to cancel out and leave hours
and the inches to cancel out and leave miles :)

Answer 16

so I just multiply them?

Answer 17

yep :)
tell me what you get ^_^

Answer 18

0ok im doing it now

Answer 19

ok I got
10764
-------
6336

Answer 20

is it right?

Answer 21

hmmm I think 21.99 times 3600 = 79164 ?

Answer 22

your right i just checked on the calculator. I guess I cant rely on bings calculator anymre..what do I do now?

Answer 23

well 79164 divided by 6336 = the answer you need :)

Answer 24

12.49?

Answer 25

yes! that's what I got! :D

Answer 26

so the answer is 12.49 miles per hour?

Answer 27

correct! ^_^

Answer 28

thanks you so much!

Answer 29

hehe you're welcome :)

Answer 30

:) bye

Answer 31

are you sure thts the answer, my friend got 0.063

Answer 32

it should be right

Answer 33

kk thanks

Answer 34

do you have the textbook in front of you?
if it is an odd number problem, the answer should be in the back of the book