Breaking Strength of String & Physics

Tensile Strength

• The types of materials from which a string is made and the way it is made -- such as a single strand, braiding or twisting -- can have an impact on its tensile strength. Testing the differences in the tensile strength of different strings made in various ways using the same materials can give you an idea on how the way a string is made impacts the tensile strength of that string. The total tensile strength dictates how much pressure a string can endure before it breaks.

Other Impacting Factors

• The type of material and the way in which a string is constructed aren't the only factors that impact the tensile strength of the string. For instance, the length of the string can have an impact. A shorter string is more difficult to create a stronger force and thus would not break as easily, increasing its tensile strength. The speed at which the string moves while attached to an object also can have an impact on the tensile strength. Faster speeds decrease the tensile strength of the string.

Testing Tensile Strength

• The tensile strength can be calculated by the amount of weight it takes for the string to break. Simply tying a weight to the end of the string and adding additional weight until the string breaks can give you an idea of its tensile strength. This method won't yield the strength in Newtons, though. Instead, you can determine a more accurate reading by spinning the object at the end of the string. Swinging the object in a circular motion allows you to observe at which point the string reaches its tensile strength. Take note of the speed of the object and the amount of time it took to travel in a full circle at the time the string breaks.

Tensile Strength Calculation

• When the string breaks, you need to know how fast the object was moving and how quickly it reached that speed. To calculate the tensile strength, you need to multiply the mass of the object tied to the string by the acceleration. To calculate the acceleration, subtract the final speed from the initial speed. Then divide that number by the amount of time it took to travel a full circle. This will give you the tensile strength reading in Newtons.