Question

the period of a simple pendulum on the surface of earth is T. At an attitude of half of the radius of earth from the surface, its period will be

Answer 1

A pendulum could not exist at the center of the Earth. Hypothetically, if it could exist, it would remain stationary. A pendulum requires gravity in order to work. There is no net gravity at the center of the earth because any object that existed there would feel equal attraction from the mass of the earth in every direction around it.