A horizontal beam is pivoted at $O$ as shown in the figure. Find the mass $m$ to make the scale straight …….. $kg.$

In an experiment with a beam balance on unknown mass $m$ is balanced by two known mass $m$ is balanced by two known masses of $16\, kg$ and $4\, kg$ as shown in figure. The value of the unknown mass $m$ is ……. $kg$.

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 metal bar $70 \;cm$ long and $4.00 \;kg$ in mass supported on two knife-edges placed $10\; cm$ from each end. A $6.00 \;kg$ load is suspended at $30\; cm$ from one end. Find the reactions at the knifeedges. (Assume the bar to be of uniform cross section and homogeneous.)

Two like parallel forces $20 \,N$ and $30 \,N$ act at the ends $A$ and $B$ of a rod $1.5 \,m$ long. The resultant of the forces will act at the point ……..