# Verify My Calculations for Pulley System: Exploring Weight and Movement

• Mopar_Mudder
In summary, The friction in the system balances the forces on the scale, so the reading is less than the tensile force applied.
Mopar_Mudder
Would really be a big help if someone could look at my drawing and verify what I have come up with.

Basically pulleys with cable wrapped around then and a weight hanging off the bottom. What I am interested in is what the wight pull at the pull scale would be and if their is any left or right movement of the scale.

I come up with aprox 51.5# of pull at the scale and pull is equal in both directions so it shouldn't be pulled left or right.

Thanks for looking.

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• Pulley Caculations.jpg
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Mopar_Mudder: Your answer in post 1 looks correct, for a frictionless system. The tensile force applied to each side of the scale would be approximately 229.3 N. The force on the scale actually would be slightly imbalanced (228.9 N to the left, and 229.6 N to the right), but the friction in the system is probably sufficient to prevent the scale from moving to the right. In fact, the scale reading might be significantly less than 228.9 N, due to losses to friction in the pulley axles.

Last edited:
The scale can't be "unbalanced". Ignoring friction, if the rope tensions on the two sides of the scale were different, the scale would move sideways.

If the tension shown the scale is T, the tensions in the two vertical ropes are
(3/7.72)T and (1.55/4)T and the sum of those tensions = 40lb. The OP's answer is correct.

Welcome to Physics Forums, Mopar_Mudder
Mopar_Mudder said:
Any good forums for "hobby" engineers to get help?

Thanks
You're fine here. Just for future reference, it never hurts to show your calculations, and it might help get a faster response.

I also agree with the 51.5 lb result. It helps make the calculations easier that the two pulley ratios (3/7.72) and (1.55/4) are equal, so the two bottom ropes must have identical 20 lb tensions.

Thanks for all the replys and help. Been a few years since I was that deep into calculations so I just wanted to make sure what I was doing was correct. Not worried about the friction in the system. For this project close is close enough.

I'll make sure I post up calcs next time.

## What does it mean to "verify" calculations?

To "verify" calculations means to check and confirm the accuracy of the calculations by using a different method or source.

## Why is it important to verify calculations?

Verifying calculations is important because it helps to ensure that the results are accurate and reliable. It also helps to identify any errors or mistakes that may have been made during the calculation process.

## How do you verify calculations?

Calculations can be verified by using a different method or formula, double-checking the calculations, or having someone else review and confirm the results.

## What are common mistakes that can occur during calculations?

Common mistakes that can occur during calculations include incorrect data input, using the wrong formula or method, incorrect units or conversions, and simple mathematical errors such as addition or multiplication mistakes.

## What should I do if my calculations are not accurate?

If your calculations are not accurate, you should check your work for any mistakes or errors. If you are unable to identify the issue, you may need to seek help from a colleague or consult additional resources to verify the calculations.

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