Two masses $A$ and $B$ of mass $M$ and $2M$ respectively are connected by a compressed ideal spring. The system is placed on $a$ horizontal frictionless table and given $a$ velocity $u\, \hat k$ in the $z$ -direction as shown in the figure. The spring is then released. In the subsequent motion the line from $B$ to $A$ always points along the $\hat i$ unit vector. At some instant of $\rho$ time mass $B$ has $a$ $x$ -component of velocity as $V_x\, \hat i$ . The velocity ${\vec V_A}$ of as $A$ at that instant is

A ball of mass $100 \,g$ is dropped from a height $h =$ $10\, cm$ on a platform fixed at the top of vertical spring (as shown in figure). The ball stays on the platform and the platform is depressed by a distance $\frac{ h }{2}$. The spring constant is.......... $Nm^{-1}$ . (Use $g=10\, ms ^{-2}$ )

Write the dimensional formula of $\frac {k}{m}$.

A vertical spring with force constant $k$ is fixed on a table. A ball of mass $m$ at a height $h$ above the free upper end of the spring falls vertically on the spring so that the spring is compressed by a distance $d.$ The net work done in the process is

A body of mass $ 0.1 kg $ moving with a velocity of $10 m/s$  hits a spring (fixed at the other end) of force constant $ 1000 N/m $ and comes to rest after compressing the spring. The compression of the spring is .............. $\mathrm{m}$

An elastic spring under tension of $3 \mathrm{~N}$ has a lengtha. Its length is $b$ under tension $2 \mathrm{~N}$. For its length$(3 a-2 b)$, the value of tension will be_______. $\mathrm{N}$.