Two particles of masses m1​=2.0 kg and m2​=5.0m1​ move in a plane and interact by a potential energy U(r)=0.5kr2,k being a constant. At time t=0, the a) Find the reduced mass of the system of two particles. b) Write down the Lagrangian in terms of R and r (from last lecture). c) Find the momentum of the CM after a minute has passed. d) How far has CM moved in a minute?