Mercury is poured into a glass U-tube. Normally, the mercury stands at equal heights in the two columns, but, when disturbed, it oscillates back and forth from arm to arm. (See Fig. 11-6.) One centimeter of the mercury column has a mass of 15.0 g. Suppose the column is displaced as shown and released, and it vibrates back and forth without friction. Compute (a) the effective spring constant of the motion and (h) its period of oscillation.