$A$ mass of $10 \; kg$ is suspended by a rope of length $4 \; m$ from the ceiling. $A$ force $F$ is applied horizontally at the mid-point of the rope such that the top half of the rope makes an angle of $45^{\circ}$ with the vertical. Then $F$ equals ........... $N$ (Take $g = 10 \; ms^{-2}$ and the rope to be massless).

An arrangement of a spring,strings,a pulley,and masses is shown in the figure below. The pulley and the strings are massless and $M > m$. The spring is light with spring constant $k$. If the string connecting $m$ to the ground is detached,then immediately after detachment,

The acceleration of the $2\,kg$ block if the free end of the string is pulled with a force of $20\,N$ as shown in the figure is:

$250 \; N$ force is required to raise a $75 \; kg$ mass using a pulley system. If the rope is pulled by $12 \; m$ and the load is lifted by $3 \; m$,the efficiency of the pulley system will be ......$\%$

$A$ frictionless pulley is attached to one arm of a balance and a string passed around it carries two masses $m_1$ and $m_2$. The pulley is provided with a clamp due to which $m_1$ and $m_2$ do not move with respect to each other. On removing the clamp,$m_1$ and $m_2$ start moving. How much change in counter mass has to be made to restore balance?

$A$ light unstretchable string passing over a smooth light pulley connects two blocks of masses $m_1$ and $m_2$. If the acceleration of the system is $\frac{g}{8}$,then the ratio of the masses $\frac{m_2}{m_1}$ is: