1. The problem statement, all variables and given/known data A piece of taffy slams into and sticks to another identical piece of taffy that is at rest. The momentum of the two pieces stuck together after the collision is the same as it was before the collision, but this is not true of the kinetic energy, which is partly turned into heat. What percentage of the kinetic energy is turned into heat? (my own addition) What if the initial piece of taffy was twice as massive as the one at rest when it collided? 2. Relevant equations 3. The attempt at a solution Something with the equation for kinetic energy? Or is it conservation of momentum because of twice the mass and the same velocity? Not sure how the second relates to loss of energy for friction.