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

$A$ heavy iron bar of weight $W$ has one end on the ground and the other on the shoulder of a person. The bar makes an angle $\theta$ with the horizontal. The weight experienced by the person is:

Explain the construction and working of an ideal lever and also explain the principle of moments of force.

$A$ metre scale is supported on a wedge at its centre of gravity. $A$ body of weight '$W$' is suspended from the $20 \text{ cm}$ mark and another weight of $25 \text{ g-wt}$ is suspended from the $74 \text{ cm}$ mark to balance it, and the metre scale remains perfectly horizontal. Neglecting the weight of the metre scale, the weight of the body is: (in $\text{ g-wt}$)

$A$ heavy iron bar of mass $12 \,kg$ has one end on the ground and the other on the shoulder of a man. The rod makes an angle $60^{\circ}$ with the horizontal. The weight experienced by the man is:

An $L$-shaped object,made of two thin rods of uniform mass density and equal length $a$,is suspended from a string as shown in the figure. If $AB = BC = a$,and the angle made by $AB$ with the downward vertical is $\theta$,then: