In a book I was reading about SHM it stated:
If the length of a simple pendulum is increased to such an extent that $\ell\to\infty$, then its time period is given by,
$$T=2\pi\sqrt\frac{R}{g}\approx84.6\text{ min}$$
Now I have many confusions like:
Doesn't the gravity change with such a large length and amplitude?
How can an infinitely long pendulum have a confined time period?
Some parts near the end may have a velocity greater than light.