# Calculating error in pendulum motion

In summary: I plugged all the values into the equation but what bothers me is the size of the error. For 20 cycles I get g=9.776, but my error is 0.02. This seems like a huge error, and would mean that my g would equal to 9.78. Anyone sees any mistake?I don't see any mistakes. Why do you think your error is "huge"?I think it's huge because it would mean that I can trust my g only to 3 sig figs. So I pretty much throw away one sig fig.3 sig figs seems OK to me.

## Homework Statement

I have to calculate the propagated error on g of pendulum. I pretty much measured the T of pendulum and now calculating g while increasing the number of cycles.

## Homework Equations

I used the equation of propagated error and i included picture of it and my calculations.

## The Attempt at a Solution

I plugged all the values into the equation but what bothers me is the size of the error. For 20 cycles I get g=9.776, but my error is 0.02. This seems like a huge error, and would mean that my g would equal to 9.78. Anyone sees any mistake?

#### Attachments

• error1.JPG
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To avoid a crick in the neck

#### Attachments

• Pend error prop.png
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TSny said:
To avoid a crick in the neck
Thanks! Makes it more convenient.

Here is picture of the equation and detail calculations.
* I don't know how to rotate the picture, sorry.

Edit: Image rotated by moderator:

#### Attachments

• IMG_2593.JPG
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* I don't know how to rotate the picture, sorry.
Most platforms have ways to rotate an image. What type of computer are you working from?

I plugged all the values into the equation but what bothers me is the size of the error. For 20 cycles I get g=9.776, but my error is 0.02. This seems like a huge error, and would mean that my g would equal to 9.78. Anyone sees any mistake?
I don't see any mistakes (but I didn't check all your calculations). Why do you think your error is "huge"?

Here, I figured it out.

#### Attachments

• IMG_2593.JPG
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TSny said:
I don't see any mistakes. Why do you think your error is "huge"?
Well I think it's huge because it would mean that I can trust my g only to 3 sig figs. So I pretty much throw away one sig fig.

3 sig figs seems OK to me. For 20 cycles you have a fractional error in T of about .001/1.44 ≅ .0007. But note that T is squared in the formula for g. So, the contribution of the error in T to the relative error in g should be roughly 2(.0007) ≅ .001. The contribution of the error in L to the relative error in g is roughly .0006/.51 ≅ .001. So, I don't think it's surprising that when you use your more accurate formula to determine the error in g, you find that you are only getting 3 sig. figs. for g.

Here, I figured it out.

You made an error in grinding the numbers here.

TSny said:
View attachment 112607
You made an error in grinding the numbers here.
Wow. Thanks a a lot. Now it makes way more sense for that cycle.

## What is the formula for calculating the error in pendulum motion?

The formula for calculating the error in pendulum motion is: error = measured value - actual value.

## How do you determine the actual value in pendulum motion?

The actual value in pendulum motion can be determined by conducting multiple trials and taking the average of the results obtained.

## What is the significance of calculating error in pendulum motion?

Calculating error in pendulum motion allows scientists to assess the accuracy and precision of their experiments and make necessary adjustments to their methods or equipment.

## What are the sources of error in pendulum motion experiments?

The sources of error in pendulum motion experiments can include air resistance, friction, and human error in measurement or timing.

## How can one minimize error in pendulum motion experiments?

To minimize error in pendulum motion experiments, it is important to use precise and accurate measurement tools, reduce external factors such as air resistance and friction, and conduct multiple trials to obtain an average value.

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