College Physics for AP® Courses 2e

# Glossary

active transport
the process in which a living membrane expends energy to move substances across
Bernoulli’s equation
the equation resulting from applying conservation of energy to an incompressible frictionless fluid: P + 1/2pv2 + pgh = constant , through the fluid
Bernoulli’s principle
Bernoulli’s equation applied at constant depth: P1 + 1/2pv12 = P2 + 1/2pv22
dialysis
the transport of any molecule other than water through a semipermeable membrane from a region of high concentration to one of low concentration
diffusion
the movement of substances due to random thermal molecular motion
flow rate
abbreviated Q, it is the volume V that flows past a particular point during a time t, or Q = V/t
fluid dynamics
the physics of fluids in motion
laminar
a type of fluid flow in which layers do not mix
liter
a unit of volume, equal to 10−3 m3
osmosis
the transport of water through a semipermeable membrane from a region of high concentration to one of low concentration
osmotic pressure
the back pressure which stops the osmotic process if one solution is pure water
Poiseuille’s law
the rate of laminar flow of an incompressible fluid in a tube: Q = (P2P1)πr4/8ηl
Poiseuille’s law for resistance
the resistance to laminar flow of an incompressible fluid in a tube: R = 8ηl/πr4
relative osmotic pressure
the back pressure which stops the osmotic process if neither solution is pure water
reverse dialysis
the process that occurs when back pressure is sufficient to reverse the normal direction of dialysis through membranes
reverse osmosis
the process that occurs when back pressure is sufficient to reverse the normal direction of osmosis through membranes
Reynolds number
a dimensionless parameter that can reveal whether a particular flow is laminar or turbulent
semipermeable
a type of membrane that allows only certain small molecules to pass through
terminal speed
the speed at which the viscous drag of an object falling in a viscous fluid is equal to the other forces acting on the object (such as gravity), so that the acceleration of the object is zero
turbulence
fluid flow in which layers mix together via eddies and swirls
viscosity
the friction in a fluid, defined in terms of the friction between layers
viscous drag
a resistance force exerted on a moving object, with a nontrivial dependence on velocity