A block of mass '3 Kg' is dropped from a height of $\;\large\frac{10}{3}\;$mts onto a mass '7 Kg' which is attached to spring of spring constant 3 N/m initially at rest . The 3 Kg mass sticks to the 7 Kg mass and then the spring starts to stretch . Find the maximum extension of the spring . (Consider inelastic collision (e=0))

Question

$(a)\;0.446\;m\qquad(b)\;0.518\;m\qquad(c)\;0.357\;m\qquad(d)\;None\;of\;these$