# Circumference of a circle HELP!!!!

• Apr 21st 2008, 01:08 PM
mchacker
Circumference of a circle HELP!!!!
Hi there people, need help again(Doh)! with simple stuff like these!
Here's the first set of questions from a math book...

The diamter of a motorcycle wheel is 65cm
a) Work out the distance, in metres, the motorcycle travels when the wheel makes 100 complete turns.
: For this one I think worked it out and here is what I have got...
65 x PI = 204.203.. x 100 = 20420.35.. ÷ 100 = 204.2 (please correct me if wrong:)

For the next question I really got confused:::

b) Work out the number of complete turns the wheel makes when the motorcycle travels 500m.

I understand all the stuff about circumference, PI, radius, diameter, area, semi-circle, but when I come upon to these question of car tyres etc. I really get confused, any tips and ideas on how to mastermind this out???

• Apr 21st 2008, 01:24 PM
Moo
Hello,

For the first one, why did you divide again by 100 ?
• Apr 21st 2008, 01:37 PM
mchacker
Well the question says, the wheel makes 100 complete amount of turns, therfore I have X it by 100, then I have divided by 100 because the question says to give the answer in meters, and the question started off by cm.(Hi) I think I am right or wrong? can you help me with the 2nd 1 please???
• Apr 21st 2008, 01:43 PM
Moo
Oh, yeah, I missed this point ^^'

For the second one...

A circumference is L=65 pi/100 (in meter).

So how many L are there in 500 ?
This is as simply as it
• Apr 22nd 2008, 01:19 PM
mchacker
hi there another question i want to ask....
There is a normal sized cylinder given, which says at the bottom of it, Base=75cm2 and 9cm. The question says, What is the area of the base?
What is the length? and What is the volume? I got really confused with this question, because it says BASE, im stupid(Headbang) I dont understand this, please help anyone!!!