check the statment are True or False $:$
$(a)$ Young’s modulus of rigid body is .....
$(b)$ A wire increases by $10^{-6}$ times its original length when a stress of
$10^8\,Nm^{-2}$ is applied to it, calculate its Young’s modulus.
$(c)$ The value of Poisson’s ratio for steel is ......
$(1)$ Infinite.
There is no strain in rigid body.
$\text { hence Young's modulus } =\frac{\text { stress }}{\text { strain }}=\frac{\text { stress }}{0}$
$=\text { infinite }$
$(2)$ $10^{14} \mathrm{Nm}^{2}$
$\mathrm{Y}=\frac{\text { Stress }}{\frac{\Delta l}{l}}=\frac{10^{8}}{10^{-6}}=10^{14} \mathrm{Nm}^{-2}$
$(3)$ $0.28$ to $0.30$
The mean distance between the atoms of iron is $3 \times {10^{ - 10}}m$ and interatomic force constant for iron is $7\,N\,/m$The Young’s modulus of elasticity for iron is
The Young's modulus of a steel wire of length $6\,m$ and cross-sectional area $3\,mm ^2$, is $2 \times 11^{11}\,N / m ^2$. The wire is suspended from its support on a given planet. A block of mass $4\,kg$ is attached to the free end of the wire. The acceleration due to gravity on the planet is $\frac{1}{4}$ of its value on the earth. The elongation of wire is (Take $g$ on the earth $=10$ $\left.m / s ^2\right):$
$(a)$ A steel wire of mass $\mu $ per unit length with a circular cross section has a radius of $0.1\,cm$. The wire is of length $10\,m$ when measured lying horizontal and hangs from a hook on the wall. A mass of $25\, kg$ is hung from the free end of the wire. Assuming the wire to be uniform an lateral strains $< \,<$ longitudinal strains find the extension in the length of the wire. The density of steel is $7860\, kgm^{-3}$ and Young’s modulus $=2 \times 10^{11}\,Nm^{-2}$.
$(b)$ If the yield strength of steel is $2.5 \times 10^8\,Nm^{-2}$, what is the maximum weight that can be hung at the lower end of the wire ?
Two similar wires under the same load yield elongation of $0.1$ $mm$ and $0.05$ $mm$ respectively. If the area of cross- section of the first wire is $4m{m^2},$ then the area of cross section of the second wire is..... $mm^2$
A metal wire of length $L_1$ and area of cross section $A$ is attached to a rigid support. Another metal wire of length $L_2$ and of the same cross sectional area is attached to the free end of the first wire. A body of mass $M$ is then suspended from the free end of the second wire. If $Y_1$ and $Y_2$ are the Youngs moduli of the wires respectively, the effective force constant of the system of two wires is :