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Honors Physics Chapter 8 Fluid Mechanics Vocabulary

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Fluid
a nonskid state of matter in which the atoms or molecules are free to move past each other, as in a gas or a liquid
Equation for mass density
mass density=mass/volume
Mass Density
the concentration of the mass of an object, measured in mass per unit volume of a substance
Buoyant Force
the upward force exerted by a liquid on an object immersed in or floating on the liquid
magnitude of buoyant force=_____ of ___ _____
weight, fluid, displaced
Liquids have a definitive ______, gases do not
volume
Mass density is ___ per unit of ____ of a substance
mass, volume
Solids and liquids tend to be almost ______, meaning that their density changes very little with changes in pressure
incompressible
Buoyant forces can keep objects _______
afloat
Pressure
the magnitude of the race on a surface per unit area
Pressure=_____/_____
force, area
Applied pressure is transmitted equally throughout a ______
fluid
What is Pascal's Principle?
Pressure applied to a fluid in a closed container is transmitted equally to every point of the fluid and to the walls of the container
Pressure varies with _____ in ______
depth, fluid
Absolute pressure= ______ pressure+(density*___-___ acceleration)
atmospheric, free
Ideal Fluid
a fluid that has no internal friction or viscosity and is incompressible
What is the continuity equation?
areaspeed in region1=area speed in region 2
The speed of fluid depends on cross-sectional ____
area
What is Bernoulli's Principle?
the pressure in a fluid decreases as the fluid's velocity increases

ex.) as air flows around an airplane wing, air above moves faster than air below, producing a lift
A _____ is a material that can flow, and thus it has no definite shape. Both _____ and liquids are fluids
fluid, gases
What is the relationship between liquid pressure and depth of a liquid? Between liquid pressure and density?
liquid pressure increases with depth; it increases with density
How does water pressure 1 meter below the surface of a small pond compare with water pressure 1 meter below the surface of a huge lake?
they are equal
If you immerse a tin can with a small hole in it in water so that water spurts through the hole, what will be the direction of water flow where the hole is?
perpendicular to the surface of the can
Why does the buoyant force act upward for an object submerged in water?
there is a greater pressure against the bottom
How does the buoyant force that acts on a fish compare with the weight of the fish?
same
Why does the buoyant force on submerged objects not act sideways?
pressure of each side is the same
the upward force that acts in the opposite direction of gravity
Buoyancy Force
When the weight of a submerged object is greater than the buoyant force, the object will?
sink
When the weight is equal to the buoyancy force, the submerged object will?
remains at any level
When the weight is less than the buoyant force, the object will?
rise to the surface and float
when water is pushed aside by an object
displaced
What are the 3 simple rules when it comes to sinking and floating?
1) an object more dense than the fluid in which it is immersed sinks
2) an object less dense than the fluid sinks
3) an object with equal density to the fluid neither sinks nor floats
Is the weight of the displaced water or the the weight of the submerged object the buoyant force when an object is completely submerged?
the weight of the displaced water
What is the SI unit of pressure?
Pascal; Pa
After a long class, a physics teacher stretches out for a nap on a bed of nails how is this possible?
The weight of the teacher would be spread out across the nails rather than all centered on one, preventing the nails going through the body of the teacher.
If an inflated beach ball is placed beneath the surface of a pool of water and released it shoots upward, out of the water. use archimedes' principle to explain why...
Archimedes principal is: "The upward buoyancy force is equal to the magnitude of the weight of fluid displaced by the body". So, the upwards force on the beach ball is equal to the weight ot the water idisplaced when pushed underwater.
Moving fluids can exhibit ________ (smooth) flow or______ (irregular) flow
laminar, turbulent
An ______ ______ is a fluid that has no internal friction or viscosity and is incompressible
ideal fluid
What is the Continuity equation?
A1v1 = A2v2
The continuity equation results from ________ of ______
conservation, mass
Rate of______ = Volume/time
V/t = A1v1 = A2v2
flow
Solid objects only exert pressure in one direction.
Liquids and gases exert pressure equally in all directions.
Fluids move from areas of ______ pressure to _____ pressure.
high, low
the buoyant force will equal ... at any depth
10 N
more internal pressure means
less speed and kinetic energy
What is the SI unit of mass density?
kilograms per cubic meters
Buoyant force acts in the _____ ______ of the force of gravity
opposite direction
the apparent weight of an immersed object depends on _______
density
Water pressure increases with _____
depth
Is a large amount of pressure always caused by a large force? Explain your answer.
No. Pressure is force per unit area: p=f/a. Thus it does not require a large force to produce a large pressure.
When drinking through a straw, you reduce
the pressure in your mouth and the atmosphere moves the liquid. Could you use a straw to drink on the moon?
No, a straw will not function on the Moon because there is no atmosphere.
Steel is much denser than water. How, then, do steel boats float?
Because of the pressure of the water, forces act on the boat. The resulting force is the buoyancy force, which pushes the boat up.
Will a ship ride higher in an inland freshwater lake or in the ocean? Why?
rides higher in salt water. Because the density of the water is higher. Which means that the weight of the displaced water is higher, so the ship needs less displaced water to balance it's weight.
Explain why balloonists use helium instead of air in balloons.
Since pure Oxygen is heavier than air, a balloon filled with Oxygen would sink because of its heavier contents plus the weight of the balloon
Astronauts sometimes train underwater to simulate conditions in space. Explain why.
because of buoyancy in water your body comes up stimulating weightlessness.... hence astronauts train underwater
Lead has a greater density than iron, and both metals are denser than water. Is the buoyant force on a lead object greater than, less than, or equal to the buoyant force on an iron object of the same volume?
The two are equal because the buoyant force depends only upon the density and volume of the liquid that is displaced.
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