When a load of $5\,kg$ is hung on a wire, an extension of $3\,m$ takes place. The work done will be ....... $Joule$. (Take $g = 10\,m/s^2$)

$A$ metal wire of length $L$ is suspended vertically from a rigid support. When a body of mass $M$ is attached to the lower end of the wire,the elongation in the wire is $l$. Consider the following statements:
$(I)$ The loss of gravitational potential energy of mass $M$ is $Mgl$.
$(II)$ The elastic potential energy stored in the wire is $Mgl$.
$(III)$ The elastic potential energy stored in the wire is $\frac{1}{2} Mgl$.
$(IV)$ The heat produced is $\frac{1}{2} Mgl$.
Which of the following statements are correct?

$A$ wire of length $L$ and area of cross-section $A$ is made of a material with Young's modulus $Y$. It is stretched by an amount $x$. The work done in stretching the wire is:

Two wires of the same diameter and the same material have lengths $l$ and $2l$. If the same force $F$ is applied to each,what is the ratio of the work done in stretching the two wires?

When a $8 \,m$ long wire is stretched by a load of $10 \,kg-wt$, it is elongated by $1.5 \,mm$. The energy stored in the wire in this process is $\left(g=10 \,ms^{-2}\right)$ (in $\,J$)

On stretching a wire,the elastic energy stored per unit volume is