Solve the model in Example 3 with k = 4 and initial conditions y1 (0) = 1, y'1 (0) = 1, y2 (0)1, y'2 (0) = – 1 under the assumption that the force 11 sin t is acting on the first body and the force – 11 sin t on the second. Graph the two curves on common axes and explain the motion physically.