What will be the mass of a body at the centre of the earth as compared to other places on the earth?

$(a)$ What do you mean by free fall?
$(b)$ What happens to the direction of motion of objects during free fall?
$(c)$ $A$ stone is dropped from a height of $19.6 \, m$. Calculate:
$(i)$ Time taken to fall.
$(ii)$ How fast does it move at the end of this fall?
$(iii)$ Acceleration after $1 \, s$.

What is the effect on the weight of a body due to the revolution of the earth?

Does the acceleration with which a body falls towards the centre of the earth depend upon its mass?

The acceleration due to gravity on the surface of the Earth is:

State the universal law of gravitation. Write the $SI$ unit of $G$. The gravitational force between two objects is $100 \, N$. How should the distance between the objects be changed so that the force between them becomes $50 \, N$?