Pulley and spring are massless and the friction is absent everwhere. $5\, kg$ block is  released from rest. The speed of $5\, kg$ block when $2\, kg$ block leaves the contact  with ground is (take force constant of the spring $K = 40\, N/m$ and $g = 10\, m/s^2)$

A block $C$ of mass $m$ is moving with velocity $v_0$ and collides elastically with block $A$ of mass $m$ which connected to another block $B$ of mass $2\,m$ through a spring of spring constant $k$. What is $k$ if $x_0$ is the compression of spring when velocity of $A$ and $B$ is same?

When a spring is stretched by $2\, cm$, it stores $100 \,J$ of energy. If it is stretched further by $2 \,cm$, the stored energy will be increased by ............. $\mathrm{J}$

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 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 block of mass $m$ is pushed against a spring whose spring constant is $k$ fixed at one end with a wall. The block can slide on a frictionless table as shown in figure. If the natural length of spring is $L_0$ and it is compressed to half its length when the block is released, find the velocity of the block, when the spring has natural length