$A$ string $AB$ of unstretched length $L$ is stretched by applying a force $F$ at the mid-point $C$ such that the segments $AC$ and $BC$ make an angle $\theta$ with $AB$ as shown in the figure. The string may be considered as an elastic element with a force to elongation ratio $K$. The force $F$ is given by

What is buckling? What should be the shape of a rod for preventing buckling?

$A$ string of cross-sectional area $4 \times 10^{-6} \, m^{2}$ and length $0.5 \, m$ is connected to a rigid body of mass $2 \, kg$. The body is rotated in a vertical circular path of radius $0.5 \, m$. The body acquires a speed of $5 \, m/s$ at the bottom of the circular path. The strain produced in the string when the body is at the bottom of the circle is $\dots \times 10^{-5}$. (Use Young's modulus $Y = 10^{11} \, N/m^{2}$ and $g = 10 \, m/s^{2}$)

$A$ wire can be broken by applying a load of $200\, N$. The force required to break another wire of the same length and same material,but double in diameter,is .......... $N$.

$A$ man grows into a giant such that his linear dimensions increase by a factor of $9$. Assuming that his density remains the same,the stress in the leg will change by a factor of

$A$ metal wire is clamped between two vertical walls. At $20 ^o C$,the unstrained length of the wire is exactly equal to the separation between the walls. If the temperature of the wire is decreased,the graph between elastic energy density $(u)$ and temperature $(T)$ of the wire is: