A "ballistic pendulum" is a device (now largely obsolete, but very useful in its day) to measure the speed of a bullet as it hits a target. Let the target be a block of wood suspended from a string, as shown in the figure below. When the bullet hits, it is embedded in the wood. And then together they swing, like a pendulum, to some maximum height . What is the initial speed of the bullet (? ? ) if you know the mass of the bullet (?1 ), the mass of the block (?2 ), and the height