When a spring is stretched by $2 \ cm$,it stores $100 \ J$ of energy. If it is stretched by another $2 \ cm$,the additional energy stored is ....... $J$.

$A$ block of weight $W$ moving with velocity $v$ on a frictionless horizontal surface hits a spring of force constant $k$. The maximum compression in the spring will be at a distance of .........

What is the spring constant? On what factors does the work done by a spring depend?

$A$ ball of mass $m$ falls from a height $h$ onto a platform attached to a vertical spring. The platform is displaced by a distance $x$. What is the spring constant?

$A$ spring with spring constant $k$ is extended from $x = 0$ to $x = x_1$. The work done will be

Two particles with mass $m_1 = 16 \ kg$ and $m_2 = 2 \ kg$ slide as a unit with a common velocity of $12 \ ms^{-1}$ on a level frictionless surface. Between them is a compressed massless spring with spring constant $k = 100 \ Nm^{-1}$. The spring,originally compressed by $25 \ cm$,is suddenly released,sending the two masses,which are connected to the spring,flying apart from each other. The orientation of the spring w.r.t. the initial velocity is shown in the diagram. What is the relative velocity of separation in $ms^{-1}$,after the particles lose contact?