An elastic string of unstretched length $L$ and force constant $k$ is stretched by a small length $x$. It is further stretched by another small length $y$. The work done in the second stretching is

When an elastic spring is stretched or compressed,does its potential energy increase or decrease?

$A$ block of mass $m$ slides down an inclined plane as shown in the figure and hits a spring at the bottom,causing it to compress. If the spring constant is $K$,what is the maximum compression of the spring?

$A$ block of mass $m$ moving with speed $v$ compresses a spring through distance $x$ before its speed is halved. What is the value of the spring constant $k$?

$A$ block of mass $m$ is pushed against a spring with spring constant $k$,which is fixed at one end to a wall. The block can slide on a frictionless table as shown in the figure. If the natural length of the spring is $L_0$ and it is compressed to half its length when the block is released,find the velocity of the block when the spring reaches its natural length.

$A$ bungee jumper is jumping with the help of an elastic ideal rope (force constant $K$). The jumper steps off the bridge and falls from rest towards the river below. He does not hit the water. The mass of the jumper is $m$,and the natural length of the rope is $l$. Gravity is $g$. Assuming everything is ideal,choose the incorrect option.