Pete writes in…
Talk about retro. I hand coded this page (for the first time in years) describing my homebrew spring constant measurement experiments. This is really the starting point for solid material characterization. If you have something cool that you’ve made with that chemistry kit, you should take a look to see how you can start characterizing it, so you can model it and know what you can do with it.
6 thoughts on “Spring constant measurement”
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I love the setup, but the distance of the weight to the fixed anchor of the stem doesn’t seem to be accounted for in the math. Surely if you moved the pivot point out, you’d get a bigger deflection and measure a totally different (higher) spring constant, right?
This will work great if your application only uses the same pivot-point distance you tested with; otherwise, I think the protractor you’ve got there would be useful – use torque and angles instead of force and distance to come up with a slightly different version of Hooke’s law (I’m sure it’s been done, but I don’t know the name).
In fact, this is how I have the undergrad who my wife’s supervising doing the measurements. I was documenting this quickly after the build, and didn’t yet get to go into the details of a pivot-to-pivot measurement and the math to use. I mean to do that soon in v.2 of the documentation. Thanks for reading, though, and thanks for the useful advice to fellow readers!
Definitely a cool read, and good to know.