Hi Folks,  Some discussion on a simple vertical seismometer got me to =
thinking about a possible school project for the kids.  At one time, I =
found a simple vertical sensor on the internet, it used pvc pipe and a =
small 9"? spring.  I built it but never tested it because I had an idea =
the coil and magnet were just too undersized.  It probably works but =
would require some strong amplification, further more, I have no idea =
what the period would be.

I wonder if one could use a "Slinky"  a toy spring used by kids? They =
are about 3" in dia. and collapsed about 5" tall.  I think I will get =
one and suspend it vertically, to check its suspended length and its =
natural resonance.  I have no idea how long the spring would expand =
under its own weight?   But let's say under 8 feet. If so, maybe it =
could be hung from the ceiling and the coil and mass would be near the =
floor?

It just might be something kids would enjoy.  =20
Q. 1.  If I pull down on a spring and release it, it will move up and =
down, until it come to rest, if each cycle is 1 sec, (say a very long =
spring), is that its natural period?
Q. 2. If I put a mass on the end of the spring, will it move slower?   =
If so, is that, now its period?  Maybe 2 or 3 seconds?
Q. 3. If I could work out the construction details, what period should I =
target for a vertical sensor?
Q. 4. Are there any websites or information on using long vertical =







Hi Folks,  Some discussion on a =
simple=20
vertical seismometer got me to thinking about a possible school project =
for the=20
kids.  At one time, I found a simple vertical sensor on the =
internet, it=20
used pvc pipe and a small 9"? spring.  I built it but never tested =
it=20
because I had an idea the coil and magnet were just too =
undersized.  It=20
probably works but would require some strong amplification, further =
more, I have=20
no idea what the period would be.
 
I wonder if one could use a =
"Slinky"  a toy=20
spring used by kids? They are about 3" in dia. and collapsed about 5"=20
tall.  I think I will get one and suspend it vertically, to check =
its=20
suspended length and its natural resonance.  I have no idea how =
long the=20
spring would expand under its own weight?   But let's say =
under 8=20
feet. If so, maybe it could be hung from the ceiling and the coil and =
mass would=20
be near the floor?
 
It just might be something kids would=20
enjoy.   
Q. 1.  If I pull down on a spring =
and release=20
it, it will move up and down, until it come to rest, if each cycle is 1 =
sec,=20
(say a very long spring), is that its natural period?
Q. 2. If I put a mass on the end of the =
spring,=20
will it move slower?   If so, is that, now its period?  =
Maybe 2=20
or 3 seconds?
Q. 3. If I could work out the =
construction=20
details, what period should I target for a vertical sensor?
Q. 4. Are there any websites or =
information on=20
using long vertical springs?   Many thanks,=20
Ted