As shown in the figure,a person holds a book between their finger and thumb (the book is held at the corner). If the weight of the book is $W$,what is the torque exerted by the person on the book?

For the system to be in equilibrium,the value of mass $m$ should be .......... $kg$.

$A$ uniform rod $AB$ of length $\ell$ and mass $M$ is suspended from a point at a variable distance $x$ from end $A$,as shown. To keep the rod horizontal,a mass $m$ is suspended from its end $A$. $A$ set of $(m, x)$ values is recorded. The appropriate variables that give a straight line when plotted are:

Write the conditions for the equilibrium of a rigid body.

$A$ weightless rod is acted on by upward parallel forces of $2N$ and $4N$ at ends $A$ and $B$ respectively. The total length of the rod $AB = 3m$. To keep the rod in equilibrium,a force of $6N$ should act in the following manner:

$A$ small ball of mass $m$ is suspended from the ceiling by a string of length $L$. The ball moves along a horizontal circle with constant angular velocity $\omega$, as shown in the figure. The torque about the centre $(O)$ of the horizontal circle is