1. A planet-star system (a planet orbitting a star) has the following effective potential energy function, where L is a positive constant: L2 Gmlmg U(I)= 2m.2r2 r (a) Draw a graph the potential energy of the system versus 1". Label all stable and unstable equilibrium points. (b) Find the equation of the force as a function of r. (c) For What values of r is the force zero? attractive (negative/toward origin)? repulsive (positive/ away from origin)? ((1) Where is the potential energy is a maximum? r (e) Where is the kinetic energy a maximum