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# Uncertainites in Mean values watch

1. Hi, How would you calculate the absolute uncertainty in a mean value?

Would you add the uncertainties? Or would you work out the percentage uncertainties, add them together, then convert them back to the absolute uncertainty

2. To calculate absolute uncertainty after calculating a mean, you should find the range of the repeat readings then divide this number by 2.

To then find%uncertainty, you do this absolute value, divided by your mean, x100.

Hope that helps
3. Thank you, That was very helpful, I will give you rep 😀
4. (Original post by JSingh102)
Thank you, That was very helpful, I will give you rep 😀
No problem!☺️ (And thanks haha)
If it's for the ISA, good luck!!
5. Thanks 😀
To calculate absolute uncertainty after calculating a mean, you should find the range of the repeat readings then divide this number by 2.

To then find%uncertainty, you do this absolute value, divided by your mean, x100.

Hope that helps
Could you clarify some stuff about uncertainties for me? I'm finding some information to conflict with others...

For example, A metre ruler has a precision of 1mm, does this mean the uncertainty is ±0.01m or would it be ±0.005m?

Or if a set of scales are precise to the nearest 0.1g, would the uncertainty be ±0.1g or ±0.05g?
7. (Original post by d14m)
Could you clarify some stuff about uncertainties for me? I'm finding some information to conflict with others...

For example, A metre ruler has a precision of 1mm, does this mean the uncertainty is ±0.01m or would it be ±0.005m?

Or if a set of scales are precise to the nearest 0.1g, would the uncertainty be ±0.1g or ±0.05g?
My physics teacher told me that you use +- 1mm for a metre rule, according to the AQA Physics A guidelines.

It definitely wouldn't be +- 0.01m as that it 1cm, and 0.005 is 5mm. One mm = 1/10 of a cm = 0.01/10 = 0.001m i believe
8. (Original post by d14m)
Could you clarify some stuff about uncertainties for me? I'm finding some information to conflict with others...

For example, A metre ruler has a precision of 1mm, does this mean the uncertainty is ±0.01m or would it be ±0.005m?

Or if a set of scales are precise to the nearest 0.1g, would the uncertainty be ±0.1g or ±0.05g?
Yupp, just to add on to the above^^

Our physics teacher told us, that unless we have a range of repeat readings/values for a certain measurement, we should use the precision of that instrument. E.g a stopclock we might be using could have 0.01s as its smallest reading, so this is the absolute uncertainty for time.

However, because of every school having slightly different equipment, some precisions, such as the precision regarding volume, will differ from school to school/ person to person, depending on which jug/measuring cylinder you have available to you. The exam board recognises this, and therefore will take this into account when you use this for your uncertainties.

Hope this helps
Yupp, just to add on to the above^^

Our physics teacher told us, that unless we have a range of repeat readings/values for a certain measurement, we should use the precision of that instrument. E.g a stopclock we might be using could have 0.01s as its smallest reading, so this is the absolute uncertainty for time.

However, because of every school having slightly different equipment, some precisions, such as the precision regarding volume, will differ from school to school/ person to person, depending on which jug/measuring cylinder you have available to you. The exam board recognises this, and therefore will take this into account when you use this for your uncertainties.

Hope this helps
Yep this has cleared up the confusion! Thanks
10. (Original post by d14m)
Yep this has cleared up the confusion! Thanks
No problem!☺️

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