Capitulo 1
38 - A power plant that separates carbon dioxide from the exhaust gases compresses it to a density
of 110 kg/m3 and stores it in an unminable coal seam with a porous volume of 100 000 m3 . Find
the mass that can be stored.
41 - A tank has two rooms separated by a membrane. Room A has 1 kg of air and a volume of 0.5
m3 ; room B has 0.75 m3 of air with density 0.8 kg/m3 . The membrane is broken, and the air
comes to a uniform state. Find the final density of the air.
44 - A valve in the cylinder shown in Fig. P1.44 has a cross-sectional area of 11 cm2 with a
pressure of 735 kPa inside the cylinder and 99 kPa outside. How large a force is needed to open the
valve?
50- A piston/cylinder with a cross-sectional area of 0.01 m2 has a piston mass of 100 kg resting on
the stops, as shown in Fig. P1.50.With an outside atmospheric pressure of 100 kPa, what should the
water pressure be to lift the piston?
61 - Liquid water with density ρi s filled on top of a thin piston in a cylinder with cross-sectional
area A and total height H, as shown in Fig. P1.61. Air is let in under the piston so that it pushes up,
causing the water to spill over the edge. Derive the formula for the air pressure as a function of
piston elevation from the bottom, h.
