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42 Cards in this Set
- Front
- Back
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One of the main differences between fluids and solids
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Fluids (including gasses) will take up the size of the container while solids will remain rigid and keep form
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What is the relationship between milliliter and cubic centimeter?
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These two are equivalent so you can interconvert them
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How do you find the density of an object?
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Density is mass/volume
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What are the units for density
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kg/m^3
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What is the density of water?
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1000 kg/m^3
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What does it mean if an object has a specific gravity of less than 1 or more than 1?
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If an object has a specific gravity less than water it means that it is less dense than water while if it has a density of more than one it is more dense than water.
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If an object has a specific gravity of less than one, if it were placed on water, what does the specific gravity tell you about the object's relationship to the surface of the water?
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Take the specific gravity as a percentage of how much of the object is submerged in the water. If an object has a specific gravity of .4, then 40% of that object will SUBMERGED IN THE WATER.
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How do you calculate pressure?
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Pressure is Force per unit Area. P = F/A
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What are the units for pressure?
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Pascals
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Conversions between the different types of pressure measurements.
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1.013x10^5 Pa = 1 atm = 760 torr = 760 mm Hg
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Absolute Pressure
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Absolute pressure is the pressure exerted on an object that is submerged in a liquid. This value represents that sum of the pressure at the surface and the pressure on the object submerged in the liquid.
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Gauge Pressure
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Gauge pressure is simply the difference between the absolute pressure and the atmospheric pressure. This is calculated by simply subtracting the two values
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What is hydrostatics?
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It is the study of fluids at rest and forces exerted on them
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Pascals Principle
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This principle states that if a force is exerted on a liquid then that force will transfer directly to every part of that liquid. This means that if you put a downward force X on one end of a fluid filled pipe, the upward forces on the other end of that pipe will equivalent to the downward force that produced it. This is all relative, however, to the area of the over which the force it exerted
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What is one major exception to pascal principle?
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One of the major exceptions to this are gasses. Pascal's Principle only applies to incompressible liquids. Gasses are compressible
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Hydraulic Lift Example
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The Force/Area for both sides of the lift will be the same. You simply set up a ratio for find the the missing variable. If the problem gives you a distance, you need to use the equation volume = distance x area.
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What is the equation for the area of a circle?
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(pi)r^2
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Archimedes principle
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When an object is placed in a liquid, the object will displace a certain volume of the fluid. Give that the fluid has a certain volume, it also exerts a force. This principle states that the force acting upward on an object that is submerged in a liquid is equivalent to the volume of the fluid displaced by the liquid.
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Equation of Archimedes principle
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Force (buoyant) = volume of fluid displaced x density of fluid x g = volume of object x density of fluid x g.
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Does the density of the object come into play in the equation?
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No. The only density that we need to consider is the density of the liquid.
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Interesting way to characterize the buoyant force.
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One way to describe this force is to see it as the force the liquid displaced exerts on the object in order to return to were it once was. This is similar to newtons third law which states that for every action, there is an equal and opposite reaction.
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Why does a penny sink but a boat float?
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The reason why a boat is able to float is because the AVERAGE DENSITY of the boat it less than that of water. The guiding force in whether an object will sink or float is the average density. A penny sinks because its average density is more than that of waters
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Surface tension
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This is a property of water in that the surface of the water will exhibit a tension due to the hydrogen bonding properties of the water molecules
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Cohesion
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Cohesion is the phenomenon in which molecule of a substance will 'cohere' which means that they will display a tendency to stick together
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Adhesion
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Adhesion is a property of liquids in which the molecule so the liquid will climb up the side of the container which contains the liquid. This is one of the main reasons why capillary action works
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Viscosity
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This is like the friction a fluid feels when flowing. Something that is highly viscous will flow very slowly while a liquid that is not as viscous will flow more freely
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What types of fluid lose more energy as they flow?
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The more viscous a fluid the more energy it loses since there is much more friction involved in the fluid
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Ideal Fluids
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Ideal fluids are fluids with no viscosity, fluids that experience no resistance to flow. They behave according to the laws of conservation of energy
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Laminar Flow
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A flow of liquid in which the layers are ordered
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Turbulent Flow
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When the fluid reaches a certain critical velocity, the fluid will begin turbulent flow in which the flow of the layers are rough and disorderly.
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Feature of turbulent flow.
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-When turbulent flow occurs, laminar flow is still present but only occurs in thin fluids that are near the wall
-Much energy is lost from this system -Boundary layer is the wall - |
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How does changing the cross sectional area of a of tube change the rate flow?
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The cross sectional area does not change the VOLUMETRIC rate flow of the fluid. If a given amount of fluid is passing a certain point X in a pipe, then in all areas of the pipe the same amount of fluid will pass through. Cross sectional area does not change the VOLUMETRIC flow rate.
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Streamlines
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Line segments that are representative of the path a fluid particles
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Continuity Equation
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This equation states that there is an inverse relationship between the velocity with which a fluid travels through a fluid and the cross sectional area of the pipe through which the fluid is traveling. If the velocity goes up then the cross sectional area must go down and if the cross sectional area goes down then the velocity must go up.
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What is the relationship between pressure exerted by a fluid and velocity with which the fluid is traveling?
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They are inversely proportional. As you increase the velocity of the fluid you decrease the pressure that the fluid exerts on the side of the pipe in which it is traveling.
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Interesting way to conceptualize Bernoulli's Equation.
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One interesting way to look at this equation is to see it as the sum of static pressure and dynamic pressure at one point in a pipe will always equal the sum of the dynamic pressure and static pressure at another point in the pipe.
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What is the basic similarity between Young's Modulus and the Shear Modulus?
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Both of these moduli essentially deal with (stress/strain). In both of these cases, the stress will always be pressure which in terms of this equation will be F/A
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Young's Modulus
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This deals with forces that are perpendicular to the to the object itself. When a force acts directly on an object, the object will be compressed to a certain degree. This, however, only deals with forces that are acting perpendicularly to to object.
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Yield Strength
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The point where the object will not return to its original shape if it is subjected to a certain force
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Ultimate Strength
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The point where the object will rupture if a certain force is exerted on it
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Bulk Modulus
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This represents the extent to which an object will undergo a change of volume due to a given force
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Small number and large number vis a vis moduli
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Small numbers will represent materials that are malleable while larger number represent numbers that materials that are more rigid
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