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# What is the spacing of each ridges in a 10p coin?

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1. What is the spacing of each ridges in a 10p coin?
Hi

I have an exam tomorrow where i am to measure the spacing of each ridges on a 10P coin. I thought i could make carbon imprint of the ridges of a 10p coin and then try to measure the ridges using a meter ruler but i am unsure if i will get accurate results using that technique. Also What could be uncertainty of my measurement?
2. Re: What is the spacing of each ridges in a 10p coin?
You don't measure a single ridge.
Measure a large number and divide by that number.
This reduces the uncertainty in the measurement.
3. Re: What is the spacing of each ridges in a 10p coin?
(Original post by Stonebridge)
You don't measure a single ridge.
Measure a large number and divide by that number.
This reduces the uncertainty in the measurement.

wont that give you a value of 1?
4. Re: What is the spacing of each ridges in a 10p coin?
(Original post by arnab)
wont that give you a value of 1?
No. Why should it?
You measure the length of, say, 10 ridges and divide the length by 10.
5. Re: What is the spacing of each ridges in a 10p coin?
(Original post by Stonebridge)
No. Why should it?
You measure the length of, say, 10 ridges and divide by 10.

Ohh sorry, i was thinking of something else. MAN I feel soooo DUMB!!

Thanks again
6. Re: What is the spacing of each ridges in a 10p coin?
Count the ridges, maybe marking them with pen as you go.
Measure the diameter of the coin, find the circumference.
Divide the circumference by the total number of ridges.
7. Re: What is the spacing of each ridges in a 10p coin?
Have fun measuring a <0.5mm length with a 1m ruler.
8. Re: What is the spacing of each ridges in a 10p coin?
(Original post by JuKaMy)
Count the ridges, maybe marking them with pen as you go.
Measure the diameter of the coin, find the circumference.
Divide the circumference by the total number of ridges.

(Original post by LeeC)
Have fun measuring a <0.5mm length with a 1m ruler.
Er, no.
The simplest solution is to roll the coin carefully over a flat piece of Blu Tack (or other similar material eg plasticine) making an imprint of the grooves.
9. Re: What is the spacing of each ridges in a 10p coin?
(Original post by Stonebridge)
Er, no.
The simplest solution is to roll the coin carefully over a flat piece of Blu Tack (or other similar material eg plasticine) making an imprint of the grooves.
I know that..which is why I said have fun measuring it with a metre rule which was his original idea (sarcasm).
10. Re: What is the spacing of each ridges in a 10p coin?
(Original post by LeeC)
I know that..which is why I said have fun measuring it with a metre rule which was his original idea (sarcasm).
u r sooo funny.....
11. Re: What is the spacing of each ridges in a 10p coin?
(Original post by LeeC)
Have fun measuring a <0.5mm length with a 1m ruler.
I appreciated the wit. (Y)
12. Re: What is the spacing of each ridges in a 10p coin?
(Original post by arnab)
u r sooo funny.....
I wasn't trying to be funny, I was trying to make you think about better ways of doing it. Don't ask for help if you're going to cry about a bit of sarcasm.
13. Re: What is the spacing of each ridges in a 10p coin?
what do you guys get as the diameter of the coin? about 24mm? and what about the measurement of the ridge spacing?
14. Re: What is the spacing of each ridges in a 10p coin?
(Original post by Rajvir95)
what do you guys get as the diameter of the coin? about 24mm? and what about the measurement of the ridge spacing?
yhh i got 24.503 but i only got it that accurate because i used a digital micrometer

cant remember the actual spacing but the number of ridges was 91 for me
15. Re: What is the spacing of each ridges in a 10p coin?
EMPA?
16. Re: What is the spacing of each ridges in a 10p coin?
(Original post by Stonebridge)
No. Why should it?
You measure the length of, say, 10 ridges and divide the length by 10.
I was just thinking, for this method to work, don't you need to take into account the size of ridges themselves?

If you use the method of just counting (for example) 10 ridges, measuring the length and then dividing by 10 to find the average spacing between them, that would be flawed because it makes the assumption that the ridges themselves don't take up any spaces, right?

.......or maybe I'm overthinking this
17. Re: What is the spacing of each ridges in a 10p coin?
(Original post by internet tough guy)
I was just thinking, for this method to work, don't you need to take into account the size of ridges themselves?

If you use the method of just counting (for example) 10 ridges, measuring the length and then dividing by 10 to find the average spacing between them, that would be flawed because it makes the assumption that the ridges themselves don't take up any spaces, right?

.......or maybe I'm overthinking this
You make sure you measure from the middle (or end) of the first ridge to the middle (or end) of the last one.
If you wanted to measure, say, the wavelength of a wave, you could measure the length of 10 waves and divide by 10. This doesn't in any way assume the waves "don't take up any space". The key is to measure from the same point on the 1st wave to the same point on the last one.
18. Re: What is the spacing of each ridges in a 10p coin?
(Original post by Stonebridge)
No. Why should it?
You measure the length of, say, 10 ridges and divide the length by 10.
9 spaces, divide by 9.
19. Re: What is the spacing of each ridges in a 10p coin?
(Original post by spocckka)
9 spaces, divide by 9.
If the fancy takes you.
Measure the largest number you can for the greatest accuracy.
20. Re: What is the spacing of each ridges in a 10p coin?
(Original post by Stonebridge)
If the fancy takes you.
Measure the largest number you can for the greatest accuracy.
No, if you're going to measure the total distance for 10 ridges, as in your example, you would divide by 9 to get the space between the ridges, which is what the OP wanted. There are 9 spaces between 10 ridges.

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Last updated: May 1, 2012
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