$A$ boy is hanging from the branch of a tree as shown. For the tension in his arms to be maximum,the angle between his arms must be ............ $^o$.

$A$ body of mass $m$ is allowed to fall with the help of a string with downward acceleration $\frac{g}{6}$ to a distance $x$. The work done by the string is .............

Two bodies of mass $6 \ kg$ and $4 \ kg$ are tied to a string as shown in the adjoining figure. If the table and pulley are frictionless,then the acceleration of the $6 \ kg$ mass will be $........ \ ms^{-2}$ $\left(g=10 \ ms^{-2}\right)$.

Find the mechanical advantage for pulling mass $M$ by the person as shown in the figure.

As shown in the figure,two equal masses each of $2\, kg$ are suspended from a spring balance. The reading of the spring balance will be ......... $kg$.

Two weights $2 \,N$ and $3 \,N$ are suspended from the ends of an inextensible string passing over a fixed frictionless pulley. If the pulley is pulled up with an acceleration equal to the acceleration due to gravity $(g)$, then the tension in the string is: (in $\,N$)