The reason for the change in shape of a regular body is

$A$ wire is hanged from the ceiling without any weight below it. Would there be any stress in the wire?

$A$ rod is placed on a smooth horizontal surface. What is the stress developed when the temperature is increased by $40\,^{\circ}C$?
$[\alpha = 5\, \times\, 10^{-5}\,^{\circ}C^{-1},\, Y = 5\, \times\, 10^{11}\, N/m^2]$

$A$ $2 \,m$ long rod of radius $1 \,cm$ which is fixed from one end is given a twist of $0.8$ radians. The shear strain developed will be

What is strain? Give its units. Define longitudinal stress.

When is the force between atoms attractive? When is it repulsive?