1. The problem statement, all variables and given/known data http://imgur.com/UsKsaOn 2. Relevant equations Why is the answer in joules multiplied by 2/3 and 1/2? I can follow the rest of the problem. 3. The attempt at a solution I get the same solution as my teacher if I use the constants 2/3 and 1/2. I just don't understand where they are coming from.