Problem 4.22

Calculate the period of small oscillations of a hydrometer (Fig. 4.2) which was slightly pushed down in the vertical direction. The mass of the hydrometer is $m=50 \mathrm{~g}$, the radius of its tube is $r=3.2 \mathrm{~mm},$ the density of the liquid is $\rho=1.00 \mathrm{~g} / \mathrm{cm}^{3} .$ The resistance of the liquid is assumed to be negligible.