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 im-
pact, 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 increasing the internal energy of both
pieces.
How much of the original kinetic energy was
"lost" in this way?