Working Out Stress Of Fishing Line (Physics, Force Area etc)?

Question

Im trying to work out the stress of a fishing line after connecting a fishing line to a pulleyboard and adding 100g weights one at a time onto the fishing line to create strain and stress.

I know the formula is Stress = Force divided by area

And i have already worked out the force acting on the fishing line for each 100 gram weights which are added. If i have done this right it is 0.1 (100 g) multiplied by 9.81 (gravity) to give 0.981.

Also i have the diameter of the fishing line as 35 microns (3.5 x 10 to the power of -5)

So the area of the cross section of the circular fishing line is needed and then needs to be multiplied by the length of the fishing line which is 1.2 metres.

Can anyone help me out with this please?

Thank you so much

Answer 1

The cross-sectional area of the line is pi*r^2, not pi*d^2 as was used in the previous answer. So the stress is 0.981/(pi*r^2) = 1020 N/mm^2 (or 1.02E9 N/m^2) per 100 g weight.
Are you sure about that diameter? It's very small, even for fishing line. If using one of the new superstrength lines like silver thread, this size (if obtainable) would only have a test rating of about 0.15 lb.

Answer 2

The weights induce a stress of Force/Area in the fishing line. That is

0.981 N / (pi * (0.035 mm)^2) = 255 N/mm^2

Don't multiply this with the lenght of the line. This is the stress at every point of the line.

The deformation of the fishing line is neglected here. When the force streches the line, you have to devide the force by the (smaller) area of the streched line.