$A$ 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.........

$A$ block of mass $m$ is hung vertically from an elastic thread of force constant $\frac{2mg}{a}$. Initially,the thread is at its natural length and the block is allowed to fall freely. The work done on the block by the Earth when it passes through the equilibrium position will be:

If a spring is stretched by a force $T$,what is the potential energy stored in the spring? (Given $T$ is the tension/force and $k$ is the spring constant.)

Find the maximum tension in the spring if the spring is initially at its natural length when the block of mass $m$ is released from rest.

$A$ block of mass $m$ initially at rest is dropped from a height $h$ onto a spring of force constant $k$. If the maximum compression in the spring is $x$,then:

$A$ smooth track extends to a horizontal part as shown in the figure. $A$ spring with a force constant of $400 \ N/m$ is firmly attached to one end of this horizontal part. $A$ mass of $40 \ g$ is released from a height of $4.9 \ m$. Calculate the compression in the spring in $cm$.