7.37 To determine the viscosity of a liquid, one hangs up and small steel ball with the mass m and the radius r in a linear spring and measures the oscillation time tn, in the air and the oscillation time ta in the liquid. The resistance in the liquid is F, = 6arv where u is the viscosity and v speed. Neglect the lifting force and determine the viscosity. 7.30 A body with mass m, which is suspended in a spring with a spring constant k, is connected to the floor by a damper with a damping constant c. Determine which attenuation constant c causes the system to be critically attenuated. Then select the damping constant e / 2 and determine the movement if the body in equilibrium is given a downward velocity vo ww