$A$ uniform rod of mass $15\,kg$ and length $5\,m$ is held stationary with the help of a light string as shown. The tension in the string is ......... $N.$

Shown in the figure is a rigid and uniform one-meter-long rod $AB$ held in a horizontal position by two strings tied to its ends and attached to the ceiling. The rod has a mass $m$ and another weight of mass $2m$ is hung at a distance of $75\, cm$ from $A$. The tension in the string at $A$ is $....mg$.

$A$ uniform rod of length $200 \, cm$ and mass $500 \, g$ is balanced on a wedge placed at $40 \, cm$ mark. $A$ mass of $2 \, kg$ is suspended from the rod at $20 \, cm$ and another unknown mass $'m'$ is suspended from the rod at $160 \, cm$ mark as shown in the figure. Find the value of $'m'$ such that the rod is in equilibrium. $(g = 10 \, m/s^2)$

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. With $B$ (mass $17 \,kg$) standing on one end of the plank,the maximum mass of $A$,who can walk over the plank is close to ............ $kg$.

$A$ metre stick is balanced on a knife edge at its centre. When four coins, each of mass $2 \,g$, are placed one on top of the other at the $10.0 \,cm$ mark, the stick is found to be balanced at the $46.0 \,cm$ mark. The mass of the metre stick is: (in $\,g$)

$A$ metal rod of weight $W$ is supported by two parallel knife-edges $A$ and $B$. The rod is in equilibrium in a horizontal position. The distance between the two knife-edges is $r$. The centre of mass of the rod is at a distance $x$ from $A$. The normal reaction on $A$ is