$A$ spring with a force constant of $100 \ N/m$ is stretched by $5 \ cm$. Calculate the work done. (in $J$)

Explain the elastic potential energy of a spring and obtain an expression for this energy.

$A$ spring with force constant $k$ is initially stretched by a distance $x$. If it is further stretched by a distance $y$,the work done during the second stretching is.........

$A$ system consists of two springs connected in series,each having a spring constant of $10 \text{ N m}^{-1}$. The minimum work required to stretch this system by $1 \text{ cm}$ in $\text{erg}$ is

$A$ spring of force constant $k$ is cut into two parts at one-third of its length. When both parts are stretched by the same amount,the work done in the two parts will be:

$A$ light spring of length $10 \ cm$ is stretched by $2 \ cm$ when a mass of $20 \ g$ is attached to its end. The mass is pulled until the total length of the spring becomes $14 \ cm$. What is the elastic potential energy stored in the spring (in Joules)?