Measuring Force on a Fishing Rod: Equation and Sample Problem

[stuhr727]

I am looking into building my own fishing rod and am really lost on how to measure force exerted strictly on a pole as it bends. I think I'll have to use a strain gauge but I can't even find an equation to measure the force.

Can anyone provide the equation, variables, and sample problem? I'd like to solve for force, ill have the Modulus of Elasticity ε.

Ideally solve from the output of the strain gauge.

 

[SteamKing]

If you want to measure the force applied to the pole, put a dynamometer (force gauge) in the fishing line and pull.

Strain gauges measure strain, not force.

 

[stuhr727]

If you want to measure the force applied to the pole, put a dynamometer (force gauge) in the fishing line and pull.

Strain gauges measure strain, not force.

A dynamometer won't account for the force being distributed across the pole. All of the guides and the bend will make the force gauge reading on the line less than what it really is.

Understand strain gauges measure strain...but you can use strain to calculate force. Can someone smart reply.

 

[Oxvillian]

A dynamometer won't account for the force being distributed across the pole. All of the guides and the bend will make the force gauge reading on the line less than what it really is.

Understand strain gauges measure strain...but you can use strain to calculate force. Can someone smart reply.

Euler (who was fairly smart by most accounts ) worked out the mathematics of bent rods about 250 years ago, if that's what you're looking for. It's quite involved - lots of nasty elliptical integrals

I think you might be confused about the forces involved here. SteamKing is correct - a force gauge in the fishing line will tell you exactly the force exerted on the rod by the line. Inside the rod, life is complicated because various bits of the rod exert different forces on various other bits of the rod. It's not like there's one force "all the way through the rod". Instead, there's a continuously varying stress field.

 

[paranormal]

I can provide you with the equation and variables needed to measure the force exerted on a fishing rod. Firstly, you are correct in thinking that a strain gauge is necessary to measure this force. A strain gauge is a device that measures the strain or deformation of an object, which can be used to calculate the force exerted on the object.

The equation you will need to use is Hooke's Law, which states that the force (F) applied to an object is directly proportional to the change in length (ΔL) of the object, and is also dependent on the object's modulus of elasticity (ε). This can be written as F=εΔL.

The variables in this equation are:

F - force applied to the fishing rod
ε - modulus of elasticity of the fishing rod
ΔL - change in length of the fishing rod

To solve for force, you will need to know the modulus of elasticity of your fishing rod, which can be found in the specifications provided by the manufacturer. You will also need to measure the change in length of the fishing rod when a force is applied. This can be done using the strain gauge.

A sample problem to demonstrate the use of this equation could be as follows:

A fishing rod has a modulus of elasticity of 10,000 N/m^2. A strain gauge attached to the rod measures a change in length of 0.05 m when a force is applied. What is the force exerted on the fishing rod?

Using the equation F=εΔL, we can plug in the given values to solve for force:

F= (10,000 N/m^2)(0.05 m) = 500 N

Therefore, the force exerted on the fishing rod is 500 N.

I hope this helps you in your project of building your own fishing rod. Remember to always use proper safety precautions when conducting experiments involving force and strain. Good luck!