1. The problem statement, all variables and given/known data F=force, a=acceration, m=mass, U potential energy, P momentum, E=energy How do derive 2 and 3 from 1( see below). 2. Relevant equations 1) F=ma, 2) E= (p^2)/(2m) + U, 3) ma = -del U 3. The attempt at a solution I try to understand why U pop into the equation for 2 and 3 given only 1, but i failed. I do not know how to introduce the notion of potential energy given only 1.