# Thermal expansion and a pendulum clock

1. Sep 7, 2004

### jealey

I need a little help. The problem is as follows:

A pendulum clock with a pendulum made of brass is designed to keep accurate time at 18 °C. If the clock operates at 0.0°C, what is the magnitude of its error, in seconds per hour (use a minus sign to indicate slowing down)? The linear expansion coefficient of brass is 19 x 10-6 /C°.

I tried multiplying the change in temperature by the coefficient of brass, but that does not come out right. I also tried multiplying that answer by 3600 to get the seconds but that was not right either. What else is there to do?

2. Sep 7, 2004

### Tide

Did you use the fact that the period of the pendulum is proportional to $\sqrt L$?