Period of a simple pendulum

1. Dec 6, 2011

rbwang1225

1. The problem statement, all variables and given/known data
The usual formula for the period T of a simple pendulum of length l is T=2$\pi$$\sqrt{\frac{l}{g}}$ where g is the acceleration due to gravity. Denoting rhe inertial mass of the pendulum bob by m$_{i}$ and its gravitational mass by m$_{g}$, derive an alternative expression for T in terms of these masses, the radius R of the Earth and its mass M$_{g}$.

2. Relevant equations

3. The attempt at a solution

I just replaced g as $\frac{GM_{g} {m_{g}}}{R^{2}m_{i}}$.
I don't know if this is what the author wants.
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Dec 9, 2011

BruceW

That looks correct to me.