1. The problem statement, all variables and given/known data A bullet of mass 2.0 * 10-3 kg is fired horizontally into a free-standing block of wood of mass 4.98 * 10-1 kg, which it knocks forward with an initial speed of 1.2 m s-1. (a) Estimate the speed of the bullet. (b) How much kinetic energy is lost in the impact? (c) What becomes of the lost kinetic energy? Answers: (a) 300 m s-1; (b) 89.64 J. 2. Relevant equations - 3. The attempt at a solution (a) 2.0 * 10-3 kg * X m s-1 = 4.98 * 10-1 kg * 1.2 m s-1 X = 298.8 m s-1 (b) Kinetic energy = 1/2 * m * v2 = 0.5 * (2.0 * 10-3) * 298.8 m s-1 = 89.28 J. (c) Kinetic energy lost is potential energy gained. However, as the answers don't fit the book answers 100% and I have no answer for the (c) part, I am not sure whether I am right or wrong. Any help please? Thanks in advance for any tips.