Physical Properties of Common Liquids at 20°C Liquid Isentropic Bulk Modulusa (GN/m-) Specific Gravity (-) Benzene 1.48 0.879 Carbon tetrachloride 1.36 1.595 Castor oil 2.11 0.969 Crude oil 0.82-0.92 Ethanol 0.789 Gasoline 0.72 4.59 1.26 Glycerin Heptane Kerosene 0.886 0.684 1.43 0.82 1.44 0.88 Lubricating oil Methanol 0.796 Mercury 28.5 13.55 Octane 0.963 0.702 Seawaterb 2.42 1.025 SAE 10W oil 0.92 Water 2.24 0.998 Source: Data from References [A.1, A5, A6]. a Calculated from speed of sound: 1 GN/m² = 10 N/m² (1 N/m² = 1.45 x 10-4 lbf /in.). Dynamic viscosity of seawater at 20°C is u = 1.08 x 10-'N. s/mº. (Thus, the kinematic viscosity of seawater is about 5 percent higher than that of freshwater.) Water usually is assumed to be incompressible when evaluating static pressure variations. Actually it is 100 times more compressible than steel. Assuming the bulk modulus of water is constant,
(a) compute the percentage change in density for water raised to a gage pressure of 140 atm.
(b) Estimate the percentage change in water density as a function of p/Patm up to a pressure of 60000 psi, which is the approximate pressure used for high-speed cutting jets of water to cut concrete and other composite materials.
(c) Would constant density be a reasonable assumption for engineering calculations for cutting jets? Use Table A.2
(a) Ap/Po = %
(b) Ap/P. = %
(c) Thus constant density
a reasonable assumption for a cutting jet operating at 60000 psi. Click if you would like to Show Work for this question: