1. The problem statement, all variables and given/known data Consider 2 magnetic masses, m1 and m2; these 2 repel each other for a distance s with force f (relative to each other)...which applies from m1 to m2. Predict final velocity of m1 and m2. Assume final distance to be v1 and v2 Assume the force that f acts is constants, i.e not a function of distance. Assume the 2 masses to have an initial velocity as per 2 cases - 1)The 2 masses have initial velocity in the same direction 2)or in a different direction. Take any values pointing to the direction of motion of m1 as positive; that is the final velocity of m1 will be positive and m2 will be negative. So the f by the above definition will be negative (when real world values are taken). 2. Relevant equations We'll need 4 equations 3. The attempt at a solution Well...all have failed. As said before we need 4 equations, make it by the following facts - 2as = v^2 - u^2 (2 equations by this) Distance traveled by each mass will be different, but the summation will be equal to s. Distance traveled by each mass is also inversely proportional to its mass. I replaced this equation with law of conservation of energy's; but no go...wrong results (after checking out dynamics in spreadsheets).