Two blocks of mass $2\ kg$ and $1\ kg$ are connected by an ideal spring on a rough surface. The spring in unstreched. Spring constant is $8\ N/m$ . Coefficient of friction is  $μ = 0.8$ . Now block $2\ kg$ is imparted a velocity $u$ towards $1\ kg$ block. Find the maximum value of velocity $'u'$ of block $2\ kg$ such that block of $1\ kg$ mass never move is

A spring of force constant $10\, N/m$ has an initial stretch $0.20\, m.$  In changing the stretch to $0.25\, m$, the increase in potential energy is about.....$joule$

A ball of mass $m_1$ falls from height $h_1$ from rest to strike a spring of force constant $K$, which forces another ball of mass $m_2$ to jump on a horizontal floor at a height $h_2$ below from it. Find the horizontal distance at which ball of mass $m_2$ strikes from the position of start :- [Spring does not move]

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. maximum elongation in the spring will be

A spring $40\,mm$ long is stretched by the application of a force. If $10\, N$ force is required to stretch the spring through $1\, mm$, then work done in stretching the spring through $40\, mm$ is ............. $\mathrm{J}$

The potential energy of a certain spring when stretched through a distance $S$ is $10 \,joule$. The amount of work (in $joule$) that must be done on this spring to stretch it through an additional distance $S$ will be