# Tension Strength Physics question

• mattyc33
In summary, the conversation discussed the discovery of spider silk's ultimate strength and tensile stress, as well as the equation for calculating tensile stress. A question was then posed about the minimum diameter of a spider silk fibre needed to support the weight of someone with a mass of 63.2kg. The conversation ended with a clarification on the units for the tensile strength of spider silk.

#### mattyc33

In the course of the above research, they discovered that this spider silk has an ultimate strength #or
tensile strength of 1850mPa (see 11.4 in University Physics). Tensile stress is a measure of the
pressure in an object when it is stretched. Tensile strength is the maximum tensile stress that the
object can endure before breaking. The equation for tensile stress is Tensile Stress=F/A

where is the applied force F and A is the cross-sectional area of the object (in this case, the circle
formed by a cross-section of a fibre).

Ok, phew, so on to the question...

If Spiderman has mass 63.2kg , what is the minimum diameter of fibre (of C. darwini spider silk) required to support his weight?

I know that the area of a circle is Pi*r^2 but when I plug everything in I always get the wrong answer. I used force as mg, which didn't work. Could anyone please help?

Check your units. Your problem statement did not indicate what units it wanted the diameter of the fibre expressed in.

I have verified that the question is needed in meters. If anyone could help me with this I would appreciate it greatly!

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Is the tensile strength of the webbing 1850 milli pascals (mPa) or 1850 mega pascals (MPa)? It makes a difference. Do you know the derived units for a pascal?