A piece of sticky taffy hangs at rest in midair on the International Space Station. Someone throws another identical piece at the hanging piece, and it sticks to it. Upon impact, the two pieces move together across the room. The momentum of the stuck-together pieces is the same as the original momentum of the thrown piece, but the kinetic energy of the stuck- together pieces is different from the kinetic energy of the thrown piece. The "lost" kinetic energy went toward deforming the pieces and making them stick together, as well as in- creasing the internal energy of both pieces. How much of the original kinetic energy was "lost" in this way?