Re: will a grandfather pendulum clock run faster or slower on a hot day? why?

It actually depends on whether the clock is expensive or not. No, I'm not kidding!! Inexpensive pendulum clocks do not have temperature-compensated pendula, while more-expensive clocks tend to have better temperature compensation.

If the pendulum is not temperature compensated it will increase in length as the temperature increases, which will make it run slower.

You can find information in our archives about pendula (search on "pendulum") by using our search engine.

John Link, MadSci Physicist