read section 9. suppose that a mass m is attached to two springs in series, as shown in exercise 9.5. assume the unstretched lengths of the two springs are l and 12, respectively. the equilibrium position of the mass is thus 11 +12 verify that the following equations correctly model the physical situation, where χ represents the distance between the mass and the wall, and y represents the distance between the massless point of connection for the two springs and the wall: (a) mari =-k1(x-y-11) 0 = k1 (x-y-11)-k2(y-12) include a written explanation of the terms k, (x -y - ) and k2(y - 12), and explain the signs used on these expressions. let = x-11-12-obtain a differential equation of the form, marz-kerr z, thus showing that the mass executes simple harmonic motion about its equilibrium position. (b) dt2 (c.) identify the effective spring constant keff from problem 1. is kefs smaller or larger than k? smaller or larger than k2?