1. The problem statement, all variables and given/known data A potential energy funtion for a two dimensional force is of the form U = ax^3y + bx where a =10.51 J/m^4 and b = -8 J/m. Find the magnitude of the force that acts at the point (x,y) for x =93, y =68 2. Relevant equations F(x) = dU/dx 3. The attempt at a solution Given the PE function, I know that I have to take the derivative to find Force but I am confused as to how to do this with it being in 2-d. There are two variables, x and y. Help please.