# Isaac physics uncertainties

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#1
Why is 1/2 range the correct answer?

It would be 1/2 range for the uncertainty of the diameter but for the radius it should be 1/4 range since you're measuring across 2 radii which reduces the uncertainty by factor 2?
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#2
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#3
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2 years ago
#4
(Original post by G.Y)
Why is 1/2 range the correct answer?

It would be 1/2 range for the uncertainty of the diameter but for the radius it should be 1/4 range since you're measuring across 2 radii which reduces the uncertainty by factor 2?
(Original post by G.Y)

I think there is a typo in the question. They should be asking for the absolute uncertainty in the diameter of the wire instead of the radius. You may want to email them to verify it.
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#5
(Original post by Eimmanuel)
I think there is a typo in the question. They should be asking for the absolute uncertainty in the diameter of the wire instead of the radius. You may want to email them to verify it.
Thank you, also have another question about Isaac physics and uncertainties if you don't mind

So, on Isaac physics the absolute uncertainty is given as the value that is rounded to give the smallest measurement of an instrument, for example for a ruler with smallest measurement 1mm the absolute uncertainty would be plus/minus 0.5mm

But for my exam board the absolute uncertainty IS the smallest measurement of an instrument, so 1mm for the example above

What's the definition actually used by physicists, who's got it wrong, AQA or Isaac physics?
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2 years ago
#6
(Original post by G.Y)
Thank you, also have another question about Isaac physics and uncertainties if you don't mind

So, on Isaac physics the absolute uncertainty is given as the value that is rounded to give the smallest measurement of an instrument, for example for a ruler with smallest measurement 1mm the absolute uncertainty would be plus/minus 0.5mm

But for my exam board the absolute uncertainty IS the smallest measurement of an instrument, so 1mm for the example above

What's the definition actually used by physicists, who's got it wrong, AQA or Isaac physics?
I seem to get such question almost every year.

The question of who is right or wrong, (IMO) is like asking me - is apple or orange taste better? It may be a bad analogy.

(IMO) Both are wrong. Every scientific measuring instrument in the market has an uncertainty which is determined by the manufacturer already.

If you have the time, you may want look the writing on uncertainty by John Denker.
https://www.av8n.com/physics/uncertainty.htm

and a reference that a lot of researchers are using one way or other

https://physics.nist.gov/cuu/Uncertainty/
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#7
(Original post by Eimmanuel)
I seem to get such question almost every year.

The question of who is right or wrong, (IMO) is like asking me - is apple or orange taste better? It may be a bad analogy.

(IMO) Both are wrong. Every scientific measuring instrument in the market has an uncertainty which is determined by the manufacturer already.

If you have the time, you may want look the writing on uncertainty by John Denker.
https://www.av8n.com/physics/uncertainty.htm

and a reference that a lot of researchers are using one way or other

https://physics.nist.gov/cuu/Uncertainty/
Thank you very much
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