$A$ massless spring of force constant $K$ is placed between two blocks of masses $m$ and $M$ on a frictionless table and compressed by an amount $x$. Upon releasing the spring,both blocks move in opposite directions. The blocks lose contact with the spring when it reaches its natural length. The speed of the block of mass $M$ at the moment of separation is:

$A$ 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 $k$?

One end of a spring of spring constant $80 \ Nm^{-1}$ and unstretched length of $30 \ cm$ is fixed at point $A$ and the other end of the spring is fitted with a smooth ring of mass $300 \ g$ as shown in the figure. The ring is allowed to slide on a horizontal rod fixed at a height of $40 \ cm$. Initially the spring makes an angle of $60^{\circ}$ with the vertical and the system of spring and ring is released from rest. The speed of the ring when the spring becomes vertical is . . . . . . $ms^{-1}$.

The system of the wedge and the block connected by a massless spring as shown in the figure is released with the spring in its natural length. Friction is absent. The maximum elongation in the spring will be:

To simulate car accidents,auto manufacturers study the collisions of moving cars with mounted springs of different spring constants. Consider a typical simulation with a car of mass $1000 \; kg$ moving with a speed $18.0 \; km/h$ on a smooth road and colliding with a horizontally mounted spring of spring constant $6.25 \times 10^{3} \; N m^{-1}$. What is the maximum compression of the spring in $m$?

$A$ spring is stretched by a distance $s$,and the potential energy stored in it is $10 \ J$. What is the work done to stretch the spring by an additional distance $s$ (in $J$)?