A spring is stretched 12 cm by a force of 9 N. (Note that by Hooke's law 12 cm is displacement, and this means that F = kx where F = 9 N is force, x = k is the spring constant.) A mass of 4 kg is hung from the spring and also attached to a damper that exerts a force in the direction opposite to the direction of motion of the mass with magnitude proportional to the speed of the mass. The damper exerts a force of 9 N when the speed is 11 m/s. If the mass is pulled 16 cm below its equilibrium position and given an initial downward velocity of 22 cm/s, find the position u (in m) of the mass at any time t (in s). (Assume that position is measured upward from the equilibrium position.) u(t) = Find the quasifrequency u (in radians per second). Note: If you enter a decimal approximation, use at least seven digits after the decimal point. Find the ratio of u to the natural frequency f of the corresponding undamped system. ulf = %3D Note: If you enter a decimal approximation, use at least seven digits after the decimal point.