Quick Thermal Dynamics Question

[benji]

So we had a "quick quiz" a while back and I forgot about it and completely bombed it. I understand everything I did wrong now except for one part... Here's the question:

A brass rod (thermal expansion coefficient of 18.5*10^-6 (deg. celsius)) is used as a pendulum in a grandfather clock. The clock keeps perfect time at 20 (deg. celsius).

What is the length of the rod? (hint: how much time does it take the pendulum of a grandfather clock to go tick-tock?)

Originally I just used:

(change in length)=(coefficient of liner expansion)(original length)(change in temperature)

* sorry I don't know all the fancy code you guys use to make everything look all pretty ;) *

...that wasn't taking into account the time it takes to go "tick-tock" and I'm pretty sure it was the wrong equation.


So how should I go about this and why?

Thanks!

 

[Doc Al]

period of a pendulum

You need to use the formula for the period of a simple pendulum:
$$T = 2\pi \sqrt{L/g}$$

 

[benji]

Okay, nevermind I figured it out. You were right ;). Thanks.