An elastic spring of negligible mass has a force constant k=4 N/m. One end of the spring is fixed to the wall and the other end touches a block of mass m = 250 kg placed on a horizontal surface. The spring is compressed by an amount x=5 cm. The coefficient of friction between the block and the .in horizontal surface is (mu) = 0.2. If the system is released, then find the speed of the block when it leaves the spring