Consider the motion of a small object of mass m inside a paraboloid (cf. Figure 5.2). The paraboloid is described by the equation x + y = az. Assume that there is no friction. The object is subject to gravity, which acts in the (negative) z-direction, i.e. the gravitational force is Fgrav = -mgez. (a) Find a potential that gives rise to Fgrav. la Figure 5.2: Paraboloid.