text: READ THIS CAREFULLY\nby conservation of energy\ntotal enegy in block remains conserved\nhence potential enegy at top pt= enegy of spring at bottom pt\nmgh=1/2kx^2\n1.3*10*h=1/2*300*12/100*12/100\nh=0.166 m [assuming g=10m/s^2]\n\nb]work done by gravity=1.3*10*12/100\n                                    =1.56 J\n\nc] work done =-kx\n                      =-300*12/100\n                      =-36J\n\nd]potential energy of block at top = K.E. energy before hitting spring\n =\n mgh=1/2mv^2\n10*0.166=1/2*1.3*v^2\nv=1.59m/s\n\ne]\nmgh=mgh/2+1/2mv^2\ngh/2=1/2v^2\nv^2=1.66\nv=1.288m/s