A 5.0 kg block of wood is attached to a spring with a spring constant of 150 N/m. The block is free to slide on a horizontal frictionless surface once the spring is stretched and released. A 1.0 kg block of wood rests on top of the first block. The coefficient of static friction between the two blocks of wood is 0.45. What is the maximum speed that this set of blocks can have as it oscillates if the top block of wood is not to slip?