Physics: An Introduction Chapter 15 -- Reference Tools and Resources

Chapter 15: Fluids
Reference Tools and Resources

Reference Tools & Resources

I. Key Terms and Phrases

fluid: a liquid or a gas.

density: a measure of the compactness of an object or substance given by its mass per unit volume.

pressure: the normal force per unit area acting on an object or within a fluid.

gauge pressure: the measure of pressure that excludes the atmospheric pressure.

Pascal's principle: the principle that an external pressure is transmitted undiminished throughout a fluid.

buoyancy: the phenomenon that fluid pressure applies an upward force on immersed objects.

Archimedes' principle: that the buoyant force equals the weight of the fluid displaced by an immersed object.

floatation: occurs when the buoyant force equals an object's weight.

equation of continuity: the equation that expresses the constant mass flow rate within a fluid.

Bernoulli's equation: the application of the work-energy theorem to fluid flow.

Torricelli's law: the equation that determines the speed with which a fluid will flow from an aperture below the surface of a fluid in an open container.

viscosity: resistance to fluid flow.

surface tension: the phenomenon that the surfaces of fluids often behave in a way similar to an elastic membrane.

II. Important Equations

Name/Topic Equation Explanation
density The density of a fluid is the mass of the fluid divided by its volume.

pressure The pressure in a fluid is the normal force per unit area.

pressure with depth The pressure in a fluid increases with depth h.

buoyancy The buoyant force on an object when a volume V is submerged in a fluid of density .

equation of continuity The equation of continuity for an incompressible fluid.

Bernoulli's equation The work-energy theorem applied to fluid dynamics

viscosity The pressure difference required to cause a viscous fluid to flow with speed v through a pipe of length L and cross sectional area A.

Name/Topic	Equation	Explanation
density		The density of a fluid is the mass of the fluid divided by its volume.
pressure		The pressure in a fluid is the normal force per unit area.
pressure with depth		The pressure in a fluid increases with depth h.
buoyancy		The buoyant force on an object when a volume V is submerged in a fluid of density .
equation of continuity		The equation of continuity for an incompressible fluid.
Bernoulli's equation		The work-energy theorem applied to fluid dynamics
viscosity		The pressure difference required to cause a viscous fluid to flow with speed v through a pipe of length L and cross sectional area A.

III. Know Your Units

Quantity Dimension SI Unit
density () [M]/L³] kg/m³

pressure (P) [M][L^-1][T^-2] Pa

coefficient of viscosity (h) [M][L^-1][T^-1]

Quantity	Dimension	SI Unit
density ()	[M]/L³]	kg/m³
pressure (P)	[M][L^-1][T^-2]	Pa
coefficient of viscosity (h)	[M][L^-1][T^-1]