Write the Newton's second law for rotational motion about a fixed axis.

How to be verify fixed axis ?

How can general body be obtained ?

Why does the internal forces acting on the centre of mass of the system be neglected ?

Write the meaning of homogeneous bodies. 

For the given figure find the acceleration of $1\, kg$ block if string is massless and mass of the pulley is $2\, kg$ and diameter of puller is $0.2\, m$ (in $m / s ^{2}$)