A gun is fired horizontally at a block of wood, which is initially at rest on a horizobntal floor. The bullet becomes imbedded in the block, and the impact causes the system to slide a certain distance, s, before coming to rest. What is the inital speed of the bullet?
(Mass of bullet=10g, Mass of block=4kg, coefficent of static friction between block and floor=0.4, s=15cm)