posted by Physics .
A 0.400 kg block of wood hangs from the ceiling by a string, and a 0.0700 kg wad of putty is thrown straight upward, striking the bottom of the block with a speed of 6.40 m/s. The wad of putty sticks to the block.
How high does the putty-block system rise above the original position of the block?
I'm confused as to what equation to use. None of them seem to fit the bill perfectly.