# Changing subject forumla

• Nov 17th 2009, 09:57 AM
febbie22
Changing subject forumla
Hi i'm actaully at uni doing engineering i'm using this equation for trifilar suspension

T=2Pie*The Square Root of I*L Divided by M*rē*g

I need to change the Subject to Find I the mass moment of inertia

Any help would be great and sorry for not actualy using the right charaters.(Hi)
• Nov 17th 2009, 10:18 AM
I4talent
Quote:

Originally Posted by febbie22
Hi i'm actaully at uni doing engineering i'm using this equation for trifilar suspension

T=2Pie*The Square Root of I*L Divided by M*rē*g
(Hi)

$\displaystyle T = 2\pi\sqrt\frac{IL}{Mr^2g}$ $\displaystyle \Rightarrow \frac{T}{2\pi} = \sqrt\frac{IL}{Mr^2g}$ $\displaystyle \Rightarrow \left(\frac{T}{2\pi}\right)^2 = \left(\sqrt\frac{IL}{Mr^2g}\right)^2$ $\displaystyle \Rightarrow \frac{T^2}{4\pi^2} = \frac{IL}{Mr^2g}$ $\displaystyle \Rightarrow \frac{\left(T^2\right)\left(Mr^2g\right)}{4\pi^2} = IL$ $\displaystyle \Rightarrow \boxed{\frac{\left(T^2\right)\left(Mr^2g\right)}{\ left(4\pi^2\right)\left(L\right)} = I}$
• Nov 17th 2009, 10:21 AM
febbie22
Cheers
Thanks alot (Clapping)
• Nov 7th 2012, 01:11 PM
curlylee93
Re: Changing subject forumla
Hey, I know this was posted years ago, but ill post this for the sake of anyone else reading it now. I may be wrong, but shouldn't u end up with:

I = (T^2*Mr^2g)/(4pi^2*L) Should L not be on the bottom?