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Re: [Phys-L] equivalence question


On 2012, Sep 13, , at 15:37, Paul Nord wrote:


Here's an imponderable question for you... Will the bob of a dropped pendulum maintain its distance from the support?

Paul


This reminds me of an AJP described experiment wherein a pendulum is supported by a cart on an inclined track**.

So imponderable refers to the P. not having any ponder?


The reason I ask is (I've posted similarly earlier.) some horologists are puzzled why the arguably best pendulum clock was "so" poor at detecting the position of the sun and moon. Several other not as "good" do well including one manufactured about a century ago. (the Synchronome at the US Naval Observatory). One horologist has suggested that the failure was due to the amplitude control of the clock. It is then thought this requires the amplitude, in addition to the beat (period) to change with g. Obviously it does if the change is not "adiabatic". So I found an elevator in Santa Clara that according to the SMD in my MacBook has a surprisingly constant acceleration for several seconds. However, even w/ a very short period I don't think it would be sufficiently adiabatic. Furthermore, the jerk is rather great. So I propose a modified Atwood's machine wherein the acceleration is obtained slowly by having the counter weight a funnel that drips sand. Before I go to the great trouble of making a 20 foot track to ensure a reasonably stable support, the counter weight, and pulley. I think my best method of data collection is a Quest 2, which I must purchase, and a rotary motion sensor suspension. The Quest 2 has an integral SMD (accelerometer).

Comments please.

** A simple exptal. demo of the p. of equivalence. W. Klein 65, p.316 ff.

bc even after reading the long threads is still confused.

p.s. After a little thought perhaps the horizontal acceleration resulting from Galileo's method (inclined track) won't affect my analysis, so I can use a RMS for both a measure of the acceleration and the amplitude and period of the P, and use my Quest 1. I still have the problem of "applying" the acceleration slowly compared to the P's period.