Define mechanical advantage in lever. 

A cylinder of mass $M$ and radius $r$ is mounted on a frictionless axle over a well. A rope of negligible mass is wrapped around the cylinder and a bucket of mass $m$ is suspended from the rope. The linear acceleration of the bucket will be

What is precession ? 

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

What is pure translational motion ?

A solid sphere rotates about a vertical axis on frictionless bearing. A massless cord passes around the equator of sphere, then passes through over a solid cylinder and then is connected to block of mass $M$ as  shown in figure. If the system is released from rest then the speed acquired by block after it has fallen through distance $h$ is