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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


    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


    Buoyant forces can keep objects _______



    the magnitude of the race on a surface per unit area


    force, area

    Applied pressure is transmitted equally throughout a ______


    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 ____


    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?


    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?


    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


    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


    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 _______


    Water pressure increases with _____


    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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