PSN-L Email List Message
Subject: Re: Different types of Pendulums
From: tchannel1@............
Date: Sat, 27 Oct 2007 17:20:04 -0600
Hi Folks, I found the wed site again.
http://www.phy.mtu.edu/~suits/PH3110/pendulums.html The two I mentioned are
called "Balanced-Like" and "Nearly Balanced"
Just wondering if anyone has worked with them. As I said I made a mock up,
with no luck. But maybe my mock up was not done correctly.
Ted
----- Original Message -----
From: "John Lahr"
To:
Sent: Saturday, October 27, 2007 4:04 PM
Subject: Re: Different types of Pendulums
> The "airplane-type" design is basically a "solid pendulum." Although the
> period can be made
> very long, the sensitivity becomes correspondingly low. I don't recommend
> this design.
>
> Cheers,
> John
>
> At 02:44 PM 10/27/2007, you wrote:
>>In a message dated 27/10/2007 22:23:56 GMT Daylight Time,
>>tchannel1@............ writes:
>>Hi Folks, Sometime in the past I saw a web site describing different types
>>of pendulums used in sensors. I don't remember their names, but
>>
>>1. one was a long vertical rod, with a center pivot, it contained a mass
>>at the top of the rod and a mass at the bottom of the rod.
>>
>>My question has to do with 1. I thought this pendulum (positioned like an
>>airplane propeller) was able to adjust it's period by moving the top and
>>or bottom mass, up or down the rod?
>>I made a simply mock up of this illustration, but was not successful in
>>any way. Can one adjust this arrangement to result in an extended period?
>>Does anyone know of this web site or one similar?
>>
>>Hi Ted,
>>
>> There are several possible systems, but you need to suspend the
>> pendulum near the middle, a small height above the centre of gravity.
>> This gives a high moment of inertia due to the masses at the ends and the
>> small restoring force due to 2x mass operating just below the suspension
>> axis. It should work fine. You can also vary the position of one of the
>> masses.
>>
>> Regards,
>>
>> Chris Chapman
>
>
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