How do we calculate experimental errors?

In summary, the student is trying to find an equation to calculate the experimental error. They don't know how to do it, and are asking for help.
  • #1
InSpiRatioNy
38
0

Homework Statement


The problem let's us graph and give values for s(m) (distance) t(s) time and delta t (s) velocity. After plotting my second graph (including error bars) I used it to get the slope and the acceleration. But then it asks to determine the experimental error. Is there any formula for that? And how should I do it?


Homework Equations


That's what I want to know.


The Attempt at a Solution


Havne't done anything because I don't know what equations. It's urgent please help!
 
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  • #2
InSpiRatioNy said:

Homework Statement


The problem let's us graph and give values for s(m) (distance) t(s) time and delta t (s) velocity. After plotting my second graph (including error bars) I used it to get the slope and the acceleration. But then it asks to determine the experimental error. Is there any formula for that? And how should I do it?

Homework Equations


That's what I want to know.

The Attempt at a Solution


Havne't done anything because I don't know what equations. It's urgent please help!

You need to estimate your measurement errors. What were the increments on the dials of the instruments you used. How might you have misread them if viewed from different angles. What other sources of error would make your readings less accurate. How do your results vary from theoretical considerations? Things like that.
 
  • #3
I don't specifically understand the question (I'm tired), but error is always calculated as:

[(actual - calculated) / (calculated)] * 100 = %error

If it seems tricky to remember, just remember that getting a low reading should give a negative error. This will help you remember how the numerator goes. The denominator is the calculated result so that you and your colleagues are all working on the same relative scale.

Understanding why the equation is set like that will help you remember it.

You need to estimate your measurement errors. What were the increments on the dials of the instruments you used. How might you have misread them if viewed from different angles. What other sources of error would make your readings less accurate. How do your results vary from theoretical considerations? Things like that.
That's usually called a tolerance. The tolerance is a measure of your precision whereas error is a measure of accuracy.
 
  • #4
LowlyPion said:
You need to estimate your measurement errors. What were the increments on the dials of the instruments you used. How might you have misread them if viewed from different angles. What other sources of error would make your readings less accurate. How do your results vary from theoretical considerations? Things like that.
hmm... That's odd I didn't use any instruments, I'm not really understanding what they are asking for though. Do they mean the error of the VALUE of the acceleration I calculated? Or do they mean the error of the acceleration in the experiment itself?


ShawnD said:
I don't specifically understand the question (I'm tired), but error is always calculated as:

[(actual - calculated) / (calculated)] * 100 = %error

If it seems tricky to remember, just remember that getting a low reading should give a negative error. This will help you remember how the numerator goes. The denominator is the calculated result so that you and your colleagues are all working on the same relative scale.

Understanding why the equation is set like that will help you remember it.


That's usually called a tolerance. The tolerance is a measure of your precision whereas error is a measure of accuracy.
Well, if I'm not given the actual value, is there another way to get it?

----

Most of the given question I poseted here https://www.physicsforums.com/showthread.php?t=272542 Everything is pretty much in there except that I didn't give all the values for the things.

I'm pretty confused with this question as well, I've never done experimental errors, and I'll have to search my text one more time but it's confusing me because I'm in advance physics now, and this seems to be begining.
 

1. What is experimental error and why is it important to calculate?

Experimental error is the difference between the measured value and the true value of a quantity. It is important to calculate because it allows scientists to determine the accuracy and precision of their experimental results, which is crucial for ensuring the validity of their findings.

2. How do we determine the sources of experimental error?

The sources of experimental error can be determined by carefully analyzing the experimental procedure and identifying potential factors that could have affected the results. These factors can include human error, equipment limitations, and external influences.

3. What is the formula for calculating experimental error?

The formula for calculating experimental error is: (Experimental Value - True Value) / True Value x 100%. This will give the percentage of error in the experimental results.

4. Can experimental error be positive or negative?

Yes, experimental error can be both positive and negative. A positive error indicates that the experimental value is greater than the true value, while a negative error indicates that the experimental value is less than the true value.

5. How can we minimize experimental errors?

Experimental errors can be minimized by using reliable and calibrated equipment, carefully following the experimental procedure, and conducting multiple trials to account for any random variations. It is also important to identify and address any potential sources of error before conducting the experiment.

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