Dividing a number w/uncert by a number w/o uncert

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SUMMARY

When dividing a number with uncertainty by a constant without uncertainty, the uncertainty should be divided by that constant. For example, dividing (4.05 +/- 0.3) by 3 results in a final value of 1.35 with an uncertainty of 0.1. This method maintains the integrity of the uncertainty calculation, confirming that the uncertainty is scaled appropriately when performing division. The correct approach is to apply the same operation to the uncertainty as is applied to the value itself.

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Homework Statement


If I have a number with an uncertainty and I want to divide it by a number without an uncertainty (ex. if it's just a constant, like pi), what do I do with the uncertainty? Is it ok to just divide the uncertainty by that number?

ex. (4.05 +/- 0.3) / 3

Do I divide the 0.3 uncertainty by 3, and that would be my uncertainty for the final answer, or do I have to do percentage uncertainties?

Homework Equations


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The Attempt at a Solution


Intuition tells me it's the first, but I'm not sure.
 
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(4.05 +/- 0.3) / 3 = (4.08 to 4.02) / 3 = 1.36 to 1.34 = 1.35 +/- 0.1

So I think you are right.
 
Yes, the uncertainty is also mulitplied (or divided, in this case) by the constant.
 
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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