In a Physics Q, (June 2010 OCR B Q 12) we have in part a. A hammer of mass 2.0Kg is used to set (a mass on a spring) into oscillation. The following observations are made. The hammer approaches with an upward velocity of 5.0 m/s There is a sharp click as the hammer hits the mass. the hammer leaves the mass with a downward velocity of 3.3 m/s (i) Why does the second observation suggest about total KEn is not conserved in the collision. (1) The mark scheme gives one mark for "Sound energy produced (at expense of KE)" Now I know that this is a standard explanation for the lack of conservation of the quantity 0.5mv^2. However, (I am asked by a student) sound carries momentum too does it not, so why does the observation not say that Momentum is not conserved.? My answer to this objection (sound carries momentum too) is that the sound carries in all directions and therefore the total loss in momentum is zero. However, I am interested in whether my answer is correct or is there a more sophisticated response?