A thin rod $MN$, free to rotate in the vertical plane about the fixed end $N$, is held horizontal . When the end $M$ is released the speed of this end, when the rod makes an angle $\alpha $ with the horizontal, will be proportional to ( see figure)

A metre scale is balanced on a knife edge at its centre. When two coins, each of mass $10\, g$ are put one on the top of the other at the $10.0\, cm$ mark the scale is found to be balanced at $40.0\, cm$ mark. The mass of the metre scale is found to be $x \times 10^{-2}$ $kg$. The value of $x$ is

A mass $'m'$ is supported by a massless string wound around a uniform hollow cylinder of mass $m$ and radius $R$. If the string does not slip on the cylinder, with what acceleration will the mass fall on release?

A uniform meter scale balances at the $40\,cm$ mark when weights of $10\,g$ and $20\,g$ are suspended from the $10\,cm$ and $20\,cm$ marks. The weight of the metre scale is …… $g$

Persons $A$ and $B$ are standing on the opposite sides of a $3.5 \,m$ wide water stream which they wish to cross. Each one of them has a rigid wooden plank whose mass can be neglected. However, each plank is only slightly longer than $3 \,m$. So, they decide to arrange them together as shown in the figure schematically. With $B$ (mass $17 \,kg$ ) standing, the maximum mass of $A$, who can walk over the plank is close to ………… $kg$