Homemade seismograph not working?

[deleted-183667]

We have built the seismograph described in the "Whole lot of shaking going on" project. I understand that the instructions are not specific in case it is also used as an engineering project. However, my daughter (6th grade) wanted to use it to test the ground movement of various substrates (concrete, asphalt, dirt/grass). So, we built the seismograph as best as we could and have not had any luck testing it on the ground. We are not getting any movement of the "arm" (with the pencil) when it is on dirt and we jump right next to it or drop a 15 pound weight. We moved it to a table top and it recorded when we bumped the table, fairly hard, but it did work. It is supposed to have a weight attached to the arm to steady it, but we found the weight to be too heavy and removed it entirely.
I've read the earlier posts about this project and they were not helpful. I did see mention of a seismograph phone "app" and have downloaded that. I supposed that we could proceed with our project using my phone. But we would prefer to use the seismograph that we have built!
Can I send you a picture if that would help?
Is it possible to see a project where they successfully built the seismograph in this manner? That might help us diagnose our problem.
Thank you~
tammi

[SciB]

Hi Tammi,

I'm not familiar with this project so I read through the Background, Methods and Procedure and like you I understand how it is supposed to work but not why yours didn't work. There are some details that were not clear to me like when they say to 'attach' the hanging beam to the stand using a dowel inserted into holes. As I understand it, the beam has to be free to swing when the base moves due to vibrations so it can't be attached very tightly. In fact, I would think it should be just resting against the upright board and not 'attached' at all. What do you think?

I did not understand what the procedure was referring to when it said: "To make the wood beam hang level over the base, you can fasten the round-headed screw, bolt, or nail securely into one end of the wood beam. This screw will rest against the wood stand, making the wood beam hang level." If the beam is connected to the stand with the dowel then why is this screw needed? The leveling should be done by adjusting the length of the wire from which the beam hangs, right?

I don't know if this helps at all. Maybe someone who has used the seismograph can tell you what to do to make it work.

Please repost if you try making some changes to the device and let us know what happened. Sorry for the problem.

Sybee