$A$ spring with a force constant of $800 \ N/m$ is stretched by $5 \ cm$. Find the work done in stretching it from $5 \ cm$ to $15 \ cm$ in $J$.

The potential energy of a long spring when stretched by $2\,cm$ is $U$. If the spring is stretched by $8\,cm$,the potential energy stored in it will be $.......\,U$.

$A$ ball of mass $m$ is dropped from a height $h$ on a platform fixed at the top of a vertical spring,as shown in the figure. The platform is depressed by a distance $x$. Then the spring constant is

$A$ block of mass $100 \ g$ moving at a speed of $2 \ m \ s^{-1}$ compresses a spring through a distance $2 \ cm$ before its speed is halved. Find the spring constant of the spring. (in $N \ m^{-1}$)

Work done on a certain spring when it is stretched to $1 \text{ mm}$ from its mean position is $10 \text{ J}$. The amount of work that must be done on the spring to stretch it further by $1 \text{ mm}$ is: (in $\text{ J}$)

When a spring is stretched by $2 \ cm$,the potential energy stored is $U$. If it is stretched by $10 \ cm$,the potential energy stored will be: