What is the total momentum of the system of particle ? 

What is rotational motion and  axis ?  

Explain with illustration the pure translation and combination of translation and rotation motion of rigid body.

How many degrees of freedom does a rotational motion about fixed axis ? 

Figure shows a small wheel fixed coaxially on a bigger one of double the radius. The system rotates about the common axis. The strings supporting $A$ and $B$ do not slip on the wheels. If $x$ and $y$ be the distances travelled by $A$ and $B$ in the same time interval, then

Which forces needed for the rotational motion about a fixed axis ?