Blr243 wrote:Fishing line can be purchased in several different strengths. If an object weighing 8 kg is attached to a long Line with a breaking strain of ten kilos and the object is travelling at 40 kph obviously the line is going to snap when the object reaches the end of the line ( assuming no stretch) ..... I’m curious. How does one go about calculating the force applied to a line when a fast moving object reaches the end of its line ? Ie , 8 kilos travelling at 40 kph ....this question I raise in the interests of purchaseing a product with an adequate breaking strain to ensure the line does not snap .......is there a simple mathematical formula ?
You need to understand stress and strain before attempting any maths on this subject.
Fishing line is rated to breaking load which is really ultimate tensile strength (stress) therefore with 10 kg breaking load it's about 98 Newtons. ( 10 kg x 9.81)
When a material is loaded with a force, it produces a stress, which then causes a material to deform. Engineering strain is defined as the amount of deformation in the direction of the applied force divided by the initial length of the material.
The youngs modulus of a material will tell you how much you can apply so it will deform and spring back to its original length, exceed the youngs modulus then it goes through inelastic deformation. Therefore before it breaks it will go through inelastic stretch how much depends on the material line is made from. A 10kg line might start going through inelastic deformation around 8kg as youngs modulus is lower than breaking load (ultimate tensile stress)
Lots of variables here because 10 kg breaking load is what we call a static load which greatly differs from a dynamic load of 8 kg fish travelling at 40 kph.
You can try looking at this link if you want to learn how to calculate dynamic loads which can also be called suddenly applied loads in this case.
https://www.google.com.au/search?source=hp&ei=2qJ7XeOdF-PA3LUPkJ2ZMA&q=suddenly+applied+load&oq=suddenly+applied+&gs_l=psy-ab.1.0.0l3j0i22i30l7.1120.6588..8770...0.0..1.742.3488.0j16j6-1......0....1..gws-wiz.......0i131j0i10.QwsKBcWpfz0If that starts getting too complicated for you then just let the line run when a fish bites and don't try to slow it down too quickly when hooked which is how people land bigger fish than what line is rated for on breaking load.
If you give a man a fish you feed him for a day, if you teach a man to fish he will sit in a boat all day drinking beer with his mates while trying to catch fish.