An elastic spring (R) of negligible mass and stiffness k = 100 N/m and of unjointturns lies in the vertical plane and carries at its lower extremity a solid (S) of mass m = 500 g. g = 10 m/s2. 1) Calculate at equilibrium, the elongation of the spring and deduce its elastic potential energy.
2) Let O be the position of the center of (S) at equilibrium. Take the zero reference of gravitational potential energy as the horizontal plane passing through O. We displace (S) from its equilibrium position at O vertically downwards by a distance5 cm. Calculate the potential energy of the system [Earth; (R); (S)].