# Homework Help: Tricky pendulum question

1. Sep 20, 2009

### Chewy0087

1. The problem statement, all variables and given/known data

3. The attempt at a solution

page 6) okay well the bit i'm not sure about here is that L(cm) seeing as it is the distance to the COM i substituted r/2 for the uniform rod and r for the one with the bob giving me;

i guess it makes sense because it would go to my simplified versions when simplified

then with the 24 hour one it's really tricky...

i worked out how much a time period would be to give a difference of 1 day + 1 second, then I worked out what the difference in r would be which gave me;

0.469K for brass and
7.429K for invar, do you think that's reasonable?

note i used the formula for a pendulum of negligible mass and a mass on the end.

and

page 10) question 6, I literally have no idea, i KNOW that it's a silly rule or something reguarding a equilateral triangle in a circle or some rule you can draw on however i'm just blank on this one, any pointers in the right direction would be great...

thanks again!

Last edited by a moderator: May 4, 2017
2. Sep 20, 2009

### Chewy0087

bump, i know it's alot to ask but some help would be great