Q.
A large block of wood of mass $M =5.99 \,kg$ is hanging from two long massless cords. A bullet of mass $m =10 \,g$ is fired into the block and gets embedded in it. The (block + bullet) then swing upwards, their centre of mass rising a vertical distance $h =9.8 \,cm$ before the (block + bullet) pendulum comes momentarily to rest at the end of its arc. The speed of the bullet just before collision is : (Take $g=9.8\, ms ^{-2}$ )

Solution: