- Heat and Molecular Physics 69
each forming right angles. The vertical
parts of the tube are filled with mercury
to half the height (Fig. 68). All of mercury
-+-1--
fcan be displaced from the tube by heating
slowly the gas in the sealed end of the tube,
which is separated from the atmospheric
air by mercury.
Determine the work A done by the gas
thereby if the atmospheric pressure is p 0 =
105 Pa, the density of mercury is pm, =13.6 x 10 (^3) kg/m 3 , and the cross-sectional
area of the tube is S = 1 cm 2.
2.40. The residual deformation of an elas-
tic rod can be roughly described by using
the following model. If the elongation of
the rod Al < xo (where xo is the quantity
present for the given rod), the force required
to cause the elongation Al is determined
by Hooke's law: F = k Al, where k is the
rigidity of the rod. If Al > xo , the force does
not depend on elongation any longer (the
material of the rod starts "flowing"). If the