Consider the situation shown in figure. The force $F$ is equal to the $m_2g/2.$ If the area of cross-section of the string is $A$ and its Young's modulus $Y$, find the strain developed in it. The string is light and there is no friction anywhere
$\frac{{{m_2}g\,\left( {2{m_1} + {m_2}} \right)}}{{AY\,\left( {{m_1} + {m_2}} \right)\,}}$
$\frac{{{m_2}g\,\left( {{m_1} + {m_2}} \right)}}{{2AY\,\left( {{m_1} + {m_2}} \right)\,}}$
$\frac{{{m_2}g\,\left( {2{m_1} + {m_2}} \right)}}{{2AY\,\left( {{m_1} + {m_2}} \right)\,}}$
None of these
A uniform plank of Young’s modulus $Y $ is moved over a smooth horizontal surface by a constant horizontal force $F.$ The area of cross section of the plank is $A.$ The compressive strain on the plank in the direction of the force is
A force of $200\, N$ is applied at one end of a wire of length $2\, m$ and having area of cross-section ${10^{ - 2}}\,c{m^2}$. The other end of the wire is rigidly fixed. If coefficient of linear expansion of the wire $\alpha = 8 \times 10{^{-6}}°C^{-1}$ and Young's modulus $Y = 2.2 \times {10^{11}}\,N/{m^2}$ and its temperature is increased by $5°C$, then the increase in the tension of the wire will be ........ $N$
In nature the failure of structural members usually result from large torque because of twisting or bending rather than due to tensile or compressive strains. This process of structural breakdown is called buckling and in cases of tall cylindrical structures like trees, the torque is caused by its own weight bending the structure. Thus, the vertical through the centre of gravity does not fall withinthe base. The elastic torque caused because of this bending about the central axis of the tree is given by $\frac{{Y\pi {r^4}}}{{4R}}$ $Y$ is the Young’s modulus, $r$ is the radius of the trunk and $R$ is the radius of curvature of the bent surface along the height of the tree containing the centre of gravity (the neutral surface). Estimate the critical height of a tree for a given radius of the trunk.
A force is applied to a steel wire ' $A$ ', rigidly clamped at one end. As a result elongation in the wire is $0.2\,mm$. If same force is applied to another steel wire ' $B$ ' of double the length and a diameter $2.4$ times that of the wire ' $A$ ', the elongation in the wire ' $B$ ' will be $............\times 10^{-2}\,mm$ (wires having uniform circular cross sections)
The following four wires are made of the same material. Which of these will have the largest extension when the same tension is applied ?