Chapter 4 Flashcards
What is matter that has no definite shape and can flow; liquid or gas?
fluids
What is the study of motion and forces in fluids
fluid mechanics
What is a theory stating that all molecules of a substance are in constant motion and move more rapidly as the objec is heated?
kinetic theory of matter
What is the state of matter that has a constant volume but can flow and change its shape?
liquid
What is the state of matter where molecules move around so quickly that they are practically unaffected by cohesion and that can vary its volume by contracting and expanding?
gas
What is the attraction between atoms or molecules of the same substance?
cohesion
What is the attraction between molecules of different substances?
adhesion
What is the tendency of a liquid to pull atoms or molecules near the surface back into the liquid, forming a “skin” or film on the surface?
surface tension
What is a curved surface of a liquid formed because of a difference in strength between cohesion of the fluid molecules and their adhesion to their container?
meniscus
What is the phenomenon in which liquids in thin tubes rise above or fall beneath their own levels because of adhesion and cohesion?
capillarity
What is the force exerted per unit of area?
pressure
What is the SI unit of pressure that is equal to one Newton per square meter?
Pascal (Pa)
What is the pressure caused by gravity pulling on a substance?
gravitational pressure
What is the principle stating that a pressure increase applied to a fluid inside a closed container will be distributed equally throughout the container?
Pascal’s principle
Who discovered Pascal’s principle?d
Blaise Pascal
What is a device that uses Pascal’s principle to multiply a force by using a small-diameter input piston and a large-diameter output piston connect by a liquis- filled reservoir?
hydraulic press
What is the ability of a gas to be easily squeezed and compacted into a smaller container?
compressibility
What is the law stating that a gas’s volume and pressure are inversely proportional when temperature is held constant?
Boyle’s Law
What is the law stating that the volume and temperature of a gas are directly proportional when pressure is held constant?
Charles’s law
What is the law stating that gas temperatures and pressure are directly related when volume is held constant?
Amonton’s law
What is the gravitational pressure of air?
atmospheric pressure
What is an empty space with no matter?
vacuum
What is a device used to measure air pressure?
barometer
Who are scientists who study the weather?
meteorologists
What is a barometer that uses an airtight metal box with thin, flexible walls to measure pressure?
aneroid barometer
What is a device used to measure alititude?
altimeter
Who was the Greek mathematician who discovered that fluids exert a buoyant force upon objects within them?
Archimedes
What is an upward force exerted by a fluis on a solid object placed in the fluid?
buoyancy
What is the principle stating that the buoyant force experienced by an object is exactly equal to the weight of the fluid displaced?
Archimedes’ principle
What is a device that is used to meausre the specific gravity of liquids?
hydrometer
What is a technique that uses Archimedes’ principle to determine the specific gravity of a solid denses than water?
hydrostatic weighing
What is a vessel that can float on top of the water or mauever beneath the surface by changing its buoyancy?
submarine
What is the state in which the weight of a submerged object equals the weight of the fluid displacement?
nuetral buoyancy
What is a flexible, gas-filled sac that allows the fish to control its buoynacy?
swim bladder
What is a type of small airship used for various applicants not requiring great speed or robustness?
blimp
What is fluid friction that tends to slow an object moving through a fluid, including air pressure?
drag
What are the four main factors that affect drag?
the shape of an object, the size of an object, the speed of an object, and the fluid’s density
What is the most important factor affecting drag?
the shape of the object
What is the scince of shaping objects to allow the smooth flow of fluids around them and reduce drag?
streamlining
What limits the height that airships can attain?
the thinning of the atmosphere
Why doesn’t a ship sink?
it is not made of solid steel; it has components filled with air
What is the force on an object that is generated by relative motion between that objects and a fluid and is perpendicular to the direction of fluid flow?
lift
What is a structure designed to produce left as it moved relative to a fluid?
foil
What type of foil is designed to work in air?
airfoil
What type of foil is designed to work in water?
hydrofoil
What are the factors that affect lift?
aspect ratio, size of the foil, angle of attack, and velocity and fluid properties
What is the angle of a foil that is relative to fluid flow?
angle of attack
What is the angle at which maximum lift is achieved?
critical angle of attack
What is the phenomenon in which a spinning cylinder or ball causes lift?
Magus effect
What is a decrease in lateral pressure exerted by a moving fluid as the fluid’s speed increases?
Bernoulli effect
