PROPERTIES OF FLUIDS
Density
Density of a fluid is defined as the ratio of mass of the fluid to its volume. Density of gases are
dependent on pressure and temperature while the density of liquid remains constant. The density
of water is 1000 kg.m-3 while density of air is 1.225 kg.m-3.
With the increase in temperature volume of fluid increases and hence mass density decreases in
case of fluids as the pressure increases volume decreases and hence mass density increases.
The mass per unit volume of a substance, usually denoted as ρ . Typical values are:
• Water: 1000 kg/m3;
• Mercury: 13546 kg/m3;
• Air: 1.23 kg/m3;
FLUIDMECHANICS 2020 PREPARED BY: ENGR. CHRISTINE L. RENOMERON 1
, PROPERTIES OF FLUIDS
Specific weight
Specific weight is defined as the weight possessed by unit volume of a fluid. Specific weight is
dependent on acceleration due to gravity as it changes from place to place. The specific weight of
water is 9.81 × 1000 N.m-3.
With increase in temperature volume increase and hence specific weight decreases. With increase
in pressure volume decreases and hence specific weight increases. Therefore specific weight =
specific density * acceleration due to gravity
FLUIDMECHANICS 2020 PREPARED BY: ENGR. CHRISTINE L. RENOMERON 2
Density
Density of a fluid is defined as the ratio of mass of the fluid to its volume. Density of gases are
dependent on pressure and temperature while the density of liquid remains constant. The density
of water is 1000 kg.m-3 while density of air is 1.225 kg.m-3.
With the increase in temperature volume of fluid increases and hence mass density decreases in
case of fluids as the pressure increases volume decreases and hence mass density increases.
The mass per unit volume of a substance, usually denoted as ρ . Typical values are:
• Water: 1000 kg/m3;
• Mercury: 13546 kg/m3;
• Air: 1.23 kg/m3;
FLUIDMECHANICS 2020 PREPARED BY: ENGR. CHRISTINE L. RENOMERON 1
, PROPERTIES OF FLUIDS
Specific weight
Specific weight is defined as the weight possessed by unit volume of a fluid. Specific weight is
dependent on acceleration due to gravity as it changes from place to place. The specific weight of
water is 9.81 × 1000 N.m-3.
With increase in temperature volume increase and hence specific weight decreases. With increase
in pressure volume decreases and hence specific weight increases. Therefore specific weight =
specific density * acceleration due to gravity
FLUIDMECHANICS 2020 PREPARED BY: ENGR. CHRISTINE L. RENOMERON 2
