A large block of wood of mass M = 5.4 kg is hanged from two long cords as shown in the figure. A bullet of mass m = 9.5 g is fired into the block, coming quickly to the rest. The block-bullet then swing upward, their center of mass rising a vertical distance h= 6.3 cm before the pendulum comes momentarily to rest. What is the speed (in m/s) of the bullet just before the collision? A) 280 B) 325 C) 412 D) 556 E) 639 m M