Emergency, derive or derivative of moment of intertia

[Clairepie]

Homework Statement

Needs to be in TODAY (yeah I know I am cutting it close!)
Derive an expression for the moment of inertia of the masses at the ends of the arms in terms of l, θ and m
Is the example question asking for the derivative or is it asking to use the terms above in an equation.

Homework Equations

I=MR^2
I=\Gamma\alpha
R=l sin θ

The Attempt at a Solution

I=(mgl)/(d^2θ/d^2t) or I=2m(l sinθ)^2
It's more the term Derive that is bugging me.

Thanks guys

 

[vela]

Derive doesn't mean differentiate. The problem is simply asking you to calculate I.

 

[Doc Al]

Derive an expression for the moment of inertia of the masses at the ends of the arms in terms of l, θ and m

The moment of inertia of what?

Is the example question asking for the derivative or is it asking to use the terms above in an equation.

I'm guessing (since you didn't give the full problem) that they just want you to express the moment of inertia of some body in terms of those quantities. Not take a derivative! Derive = 'come up with'.

 

[Clairepie]

Thanks, it seems so obvious now! Having a really bad brain fog day & you've both saved my bacon! I have the rest I think,

Thank you again with extra karma your way

(Cognitive dysfunctional) Claire