
A hollow tube, sealed at one end, has a cross-sectional area
of
. The tube contains sand so that the total mass
of the tube and sand is
. The tube floats upright in a liquid of density
, as illustrated in the figure below.
The depth of the bottom of the tube below the liquid surface is
. The tube is displaced vertically and then released. The variation with time
of the depth
is shown in the graph below.
Determine
the amplitude, in metres, of the oscillations,
the frequency of oscillation of the tube in the liquid,
the acceleration of the tube when
is a maximum.
The frequency
of oscillation of the tube is given by the expression

where
is the acceleration of free fall.
Calculate the density
of the liquid in which the tube is floating.