1. The problem statement, all variables and given/known data Im hopeless at interperating this, so ill just quote it: "The masses of the vehicles involved in the collision have significant influence on injury occurence. Suppose a large car of 2000kg and a small car of 1000kg hit head-on when both are travelling at 60km/h. The mass ratio of the cars is 2:1. On collision, if the law of conservation of momentum is applied, the larger car will slow to 20km/h and the smaller car will be instantly propelled backwards at 20km/h. The larger car has a total velocity change of 40km/h while the smaller car has one of 80km/h. It is therefor not suprising that passengers in smaller cars have more severe crash injuries Present an explanation as to why this factor is important in enhancing/reducing the risk of injury to occupants (Make specific references to physical principals involved)" Hence its not an answer so much im looking for, but an explanation. 2. Relevant equations Since its talking about injury and damage to the car, i immediatly supposed it wanted reference to the Kinetic Energy formula (E=(mv^2)/2) and probably a reference to energy loss using the conservation of momentum theory. 3. The attempt at a solution Initial Kinetic energy of the large car = 3,600,000J - the Initial Kinetic energy of the smaller car = 1,800,000J (No suprises there.) Final Kinetic energies are: 800,000J and 200,000J for the larger and smaller cars respectivly. The Kinetic energy lost in each case was: 2,800,000J and 1,600,000 for the large and smaller car respectively. This was as far as i got moreorless; I concluded at this point that it must have sustained more damage because proportional to its mass, it was being subjected to a greater change of energy. The forces applied to eachother is equal, so i cant use that as a way to explain the hightened injury. Interestingly i was expecting that the changes in energy would be the same - since the work applied to eachother was also the same. Peculiar and unexplainable (unless ive missed something and made a mistake) And that is about as far as ive come - im probably just thinking in the wrong direction, looking for the wrong things; quite common problem of mine. Any help would be appreciated. Cheers, Adam.