$A$ 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 ............ $^o$.

$A$ mass $M$ is lowered by the help of a string at a constant acceleration of $\frac{g}{2}$ for a distance $x$. What is the work done by the string?

$A$ mass of $100\,kg$ is moved with uniform velocity under the influence of force $F$. Find the force acting on the beam due to the string connected to the ceiling in $N$.

In the arrangement shown in the figure, the work done by the string on the block of mass $0.36 \,kg$ during the first second after the blocks are released from a state of rest is: (Ignore friction and the mass of the string.)
(Acceleration due to gravity, $g = 10 \,m/s^2$) (in $\,J$)

For the pulley system shown in the figure,calculate the kinetic energy of the $6\,kg$ block after $5\,s$. (Assume $g = 10\,m/s^2$)

Two masses $m_1 = 10 \ kg$ and $m_2 = 6 \ kg$ are attached to a string which passes over a frictionless smooth pulley. The acceleration of the masses is .......... $m/s^2$. (Take $g = 10 \ m/s^2$)