The value of $\text{'}\mathrm{g}\text{'}$at the centre of the earth is zero. What will be the weight of a body of mass $\mathrm{m} \mathrm{kg}$ at the centre of the earth.

Explain the meaning of the following statement:

$\text{'}1 \mathrm{kgf}=9.8 \mathrm{N}\text{'}$

A body is projected vertically upwards with an initial velocity $\mathrm{u}$. If the acceleration due to gravity is $\mathrm{g}$. the time for which it remains in air is :

An object falling freely from rest reaches the ground in $2 \mathrm{s}$. If the acceleration due to gravity is $9.8 {\mathrm{ms}}^{-2}$, the velocityof the object on reaching the ground will be: