A simple pendulum has length $L$ and small oscillations with period $T$. Assuming local gravitational acceleration is $g$, which expression correctly calculates $g$ from $L$ and $T$?

• A. $g=\frac{4{\pi }^{2}L}{T^2}$
• B. $g=\frac{2\pi L}{T}$
• C. $g=\frac{T^2}{4{\pi }^{2}L}$
• D. $g=\frac{L}{2T}$

Answer: (A)