A friend of mine is one of the people in charge of winding a clock tower. He was showing my physics class how the tower works, and we were looking at the pendulum.
Here is a photo of the pendulum in question, from this blog.
We asked the class:
Why are there weights on the top of the pendulum?
This may sound like a bit of a trick question; one can come up with many possible reasons. But I’ll tell you that the weights are put there by humans deliberately as they maintain the clock. Sometimes they add a few and sometimes they take a few off.
A student then asked why the weights don’t slip off.
For a given pendulum length and swing amplitude, what is the minimum coefficient of friction to keep the weights from sliding off?
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September 24, 2013 at 4:25 pm
“Why are there weights on the top of the pendulum?”
WAG: the length (and therefore the period) of the pendulum experiences seasonal differences due to temperature change. Putting more weight on the end when its cold stretches the cable, counteracting the contraction.
September 25, 2013 at 7:12 am
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