$A$ stone dropped from a certain height takes $4$ seconds to reach the ground. The height is: (in $, m$)

Define 'acceleration due to gravity of earth'. Does the acceleration produced in a freely falling body depend on the mass of the body? Justify your answer mathematically.

Why is the value of $g$ greater at the poles than at the equator?

$A$ stone is allowed to fall from the top of a tower $100 \, m$ high and at the same time another stone is projected vertically upwards from the ground with a velocity of $25 \, m s^{-1}$. Calculate when and where the two stones will meet? (Take $g = 10 \, m s^{-2}$).

What is the magnitude of the gravitational force between the earth and a $1 \,kg$ object on its surface (in $,N$)? (Mass of the earth is $6 \times 10^{24} \,kg$ and radius of the earth is $6.4 \times 10^6 \,m$.)

What is the acceleration of free fall?