For what reasons can the elastic behavior of a solid body be explained?

The length of a metal wire is $l_1$ when the tension in it is $T_1$,and it is $l_2$ when the tension is $T_2$. The unstretched length of the wire is

Explain longitudinal stress.

$A$ force of $10 \,N$ is required to break a wire of radius $1 \,mm$. The force required to break the wire of the same material, but radius $3 \,mm$ will be

The breaking stress of a wire depends upon

The length of an elastic string is $a$ metres when the longitudinal tension is $4 \ N$ and $b$ metres when the longitudinal tension is $5 \ N$. The length of the string in metres when the longitudinal tension is $9 \ N$ is