How to Calculate Thread Strength
According to Science Daily.com, tensile strength measures the force required to pull something such as rope, wire, or a structural beam to the point where it breaks. In physics, force is measured using the units of Newtons (N), and tensile strength is usually give in N per unit area. Because a thread is so thin, you can find a meaningful tensile strength measurement in N per meter (N/m). Calculating the tensile strength of a thread is easy to do given the length of the thread and the formula for the force to gravity:
F = mg, where m is mass and g is the acceleration due to gravity, 9.8 meter per squared second
First, the mass required to break the thread while hanging from it must be determined.
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Things You'll Need
- Thread
- Small bucket
- Balance or scale that measures in grams (pounds will work but are not ideal)
- Coins
Instructions
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1
Tie a piece of the thread to a strong beam or pole so that it hangs straight down. Ideally, the end of the thread should hang just a few inches above the ground.
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2
Tie the hanging end of the thread to the center of the small bucket's handle. Try to tie it just so the bottom of the bucket is an inch or two above the ground so it does not fall far when the string breaks.
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3
Measure the length of the thread between the pole and bucket in meters (m) and record the number.
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4
Add coins one at a time to the bucket until the thread breaks.
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5
Use your scale or balance to determine the mass of the bucket while it has the number of coins in it that were required to break the string. Record the mass in kilograms (kg). 1 kg is equal to 1,000 grams (g), so if your scale gives you a number such as 2,500 g, you will have to divide it by 1,000 to convert to kg.
Example: 2,500g / 1,000 = 2.5 kg
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6
Plug the mass value into the formula for the force due to gravity.
Example: F = mg = 2.5 kg x 9.8 meters per squared second = 24.5 N
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7
Divide the force by the length of the thread to obtain the tensile strength. For instance, if you used 2 m of thread, the tensile strength would be:
24.5 N / 2 m = 12.25 N/m
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Tips & Warnings
Note: If you have a scale that measures in pounds only, multiply the number of pounds by 0.45 to convert to kg.
References
- Photo Credit PhotoObjects.net/PhotoObjects.net/Getty Images
