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1. I'm struggling with combining uncertainties.
e.g. If I were to find the volume of a cone and its uncertainty, and I'm given that diameter of base = 15 plus/minus 0.1
height = 30 plus/minus 5

I can find the volume but what would be the uncertainty?

2. (Original post by IAmTheChosenOne)
I'm struggling with combining uncertainties.
e.g. If I were to find the volume of a cone and its uncertainty, and I'm given that diameter of base = 15 plus/minus 0.1
height = 30 plus/minus 5

I can find the volume but what would be the uncertainty?

If this is at A-Level
Find the % uncertainty in the quantities.
Then for quantities you multiply or divide, add the % uncertainties to find the total % uncertainty in the answer.
If you raise a value to a power, multiply the % uncertainty by the power.
eg squaring a quantity doubles the % uncertainty.
3. (Original post by Stonebridge)
If this is at A-Level
Find the % uncertainty in the quantities.
Then for quantities you multiply or divide, add the % uncertainties to find the total % uncertainty in the answer.
If you raise a value to a power, multiply the % uncertainty by the power.
eg squaring a quantity doubles the % uncertainty.

Thanks a lot! But when I'm working out uncertainty of r^2 , what's the uncertainty of r? because I'm given diameter and not the radius. Would radius be 7.5 plus/minus 0.05?
4. (Original post by IAmTheChosenOne)
Thanks a lot! But when I'm working out uncertainty of r^2 , what's the uncertainty of r? because I'm given diameter and not the radius. Would radius be 7.5 plus/minus 0.05?
If you are given d and need to find r, the % uncertainty in r is the same as it was in d
The actual uncertainty in r is half what it was in d.
So yes, it's ±0.05 if it was ±0.1 in d
5. (Original post by Stonebridge)
If you are given d and need to find r, the % uncertainty in r is the same as it was in d
The actual uncertainty in r is half what it was in d.
So yes, it's ±0.05 if it was ±0.1 in d
Thank you

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