Why Does Spring Constant Decrease with Increased Load?

[shaun_598]

Homework Statement

Ive worked out all of my values for my shm assignment. In the table of results i have found that my spring constant decreases with load applied.

Im stuggling to come with a good reason for this.

Number Mass (kg) Spring displacement (m) Spring constant (N/m)
1 0.05 0 n/a
2 0.1 0.0195 50.31
3 0.15 0.039 37.73
4 0.2 0.061 32.16
5 0.25 0.081 30.28

The Attempt at a Solution

So far all i can come up with is twist in the spring. That the greater load had a greater spring displacement and therefore any twist when the sping would be oscilating would be exaggerated.

Any help would be appreciated thanks

 

[gneill]

What exactly was the procedure for determining the values in your table? What comprises the mass for each entry?

 

[MrWarlock616]

What exactly was the procedure for determining the values in your table? What comprises the mass for each entry?

The table is actually from this thread.

 

[gneill]

Without knowing from an eye-witness how the experiment was conducted we can only speculate on what might cause the observed variation. As a first guess I would say that the recorded mass values are actually on the heavy side by some constant offset (systematic error?). Subtract about 0.05kg from each mass value and take another look at the results.

 

[asteriatic]

I can offer a potential explanation for why the spring constant decreases with load applied. This phenomenon could be due to the spring experiencing plastic deformation, where the bonds between the molecules in the spring material start to permanently deform and rearrange under the applied load. This would result in a change in the stiffness of the spring, causing the spring constant to decrease. This is a common behavior observed in many materials, including springs, when subjected to high enough loads.

Another possibility is that the spring is experiencing fatigue, where repeated loading and unloading causes microcracks to form in the material. This can also lead to a decrease in stiffness and a change in the spring constant.

It is also important to consider the design of the spring and how it is attached to the load. If the load is not evenly distributed along the spring, it could cause uneven deformation and result in a decrease in the spring constant.

In conclusion, there could be multiple reasons for why the spring constant decreases with load applied. Further investigation and experimentation may be needed to determine the exact cause in your specific case.