1. The problem statement, all variables and given/known data The problem consists of finding a set of 2 differential equations describing the motion of a round object moving inside a 2D-bowl, of equation y=x^2. Only data given is that the equations have to be in the form of : (x1)'=x2, and (x2)'=f(x1,x2,weight of object, gravitational acceleration, K=constant of friction). The constant of friction is used to determine the friction between the object and the bowl. The main issue here is to find f. 2. Relevant equations The curve of the bowl : y=(x1)^2. (x1)'=x2, (x2)'=f(x1,x2,m,g,K). 3. The attempt at a solution After long days of reflection, I haven't managed to come up with an intelligent attempt at the solution. Please push me in the right direction! Thank you!!