Propagation of errors addition numbers without uncertainty

In summary, when calculating uncertainty in a sum, treat constants as 100% accurate and only consider the uncertainty in the variable with uncertainty. In this case, the uncertainty in T only depends on the uncertainty in a. The uncertainty in the µk*M*g term is zero.
  • #1
Silvestor
3
0

Homework Statement


I am having trouble calculating uncertainty when a number is added to a value with uncertainty.

M = 350g
a = 0.624 [itex]\pm[/itex] 0.001
µk = 0.07
g = 9.80 m/s2

Homework Equations


T = M*a + µk*M*g


The Attempt at a Solution


T = (350g)*(0.624 m/s2) + (0.07)*(350g)*(9.80m/s2)
T= 458.5 N
D[itex]_{}t[/itex] = M*(D[itex]_{}a[/itex]) + ...
D[itex]_{}t[/itex] = (350g)*(0.001 m/s2) + ...
D[itex]_{}t[/itex] = 0.35 N + ...
 
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  • #2
If you're given that there is no uncertainty in M, g, or µk then you treat them as constants that are 100% accurate. The uncertainty in the result, then, only depends upon the uncertainty in a, as you've written. The uncertainty in the µk*M*g term is zero.
 
  • #3
thanks
 

Related to Propagation of errors addition numbers without uncertainty

1. What is the propagation of errors in addition of numbers without uncertainty?

The propagation of errors in addition of numbers without uncertainty is a method used to calculate the uncertainty or margin of error in the result of adding two or more numbers that do not have any uncertainty associated with them. This method takes into account the precision of the numbers being added and provides a range of possible values for the result.

2. How is the uncertainty calculated in the propagation of errors for addition of numbers without uncertainty?

The uncertainty in the result of adding numbers without uncertainty is calculated using the formula σresult = √(σ12 + σ22 + ... + σn2), where σ is the standard deviation or uncertainty of each number being added. This formula takes into account the precision of each number and provides a range of possible values for the result.

3. Can the propagation of errors be used for addition of numbers with uncertainty?

Yes, the propagation of errors can also be used for addition of numbers with uncertainty. In this case, the uncertainty in the result is calculated using the formula σresult = √(σ12 + σ22 + ... + σn2 + σuncertainty2), where σuncertainty is the uncertainty associated with the addition operation itself.

4. How does the precision of the numbers being added affect the uncertainty in the result?

The precision of the numbers being added directly affects the uncertainty in the result. Numbers with higher precision (more digits after the decimal point) will have a smaller uncertainty compared to numbers with lower precision. This is because more precise numbers have a smaller margin of error and therefore contribute less to the overall uncertainty in the result.

5. What are the limitations of the propagation of errors for addition of numbers without uncertainty?

The propagation of errors for addition of numbers without uncertainty assumes that the numbers being added are independent and that the addition operation is linear (the result is directly proportional to the sum of the numbers). If these assumptions do not hold true, the uncertainty calculated using this method may not be accurate. Additionally, this method does not take into account any systematic errors that may be present in the numbers being added.

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