https://engineers.academy/product/l3-nd-engineering-principles-exam-preparation/ Level 3 Engineering Principles - Fluid Systems Equations Sheet

1. LEVEL 3 ENGINEERING PRINCIPLES – FLUID SYSTEMS EQUATIONS
Hydrostatics Equations
Subject Equation Variables and Units
Fluid Density ρ =
m
V
ρ = density in kilograms per cubic
meter (kg/m3
)
m = mass in kilograms (kg)
V = volume in cubic meters (m3
)
RD = relative density (dimensionless)
ρw = density of water in kilograms per
cubic meter (kg/m3
)
P = hydrostatic pressure / pressure
head in Pascals (Pa)
g = gravity in meters per second
squared (m/s2
)
h = fluid depth in meters (m)
F = thrust force in Newtons (N)
A = area of surface subjected to water
pressure in meters squared (m2
)
Relative Density RD =
ρ
ρ
Hydrostatic
Pressure
P = ρgh
Hydrostatic Force F = ρghA
Overturning
Moment M =
ρgℎ A
3
Tubes, Pipes and Ducts
Subject Equation Variables and Units
Volume Flow
Rate
Q = vA
Q = volume flow rate in cubic meters
per second (m3
/s)
v = fluid velocity in meters per second
(m/s)
A = cross sectional area of pipe or duct
in meters squared (m2
)
ṁ = mass flow rate in kilograms per
second (kg/s)
ρ = density in kilograms per cubic
meter (kg/m3
)
v A = v A
Mass Flow Rate ṁ = ρQ