Presentation on theme: "When you catch a deep-sea fish, why does its eyes pop-out?"— Presentation transcript:
1When you catch a deep-sea fish, why does its eyes pop-out? QUICK WRITEWhy is the electricity produced at the bottom of dams?When you catch a deep-sea fish, why does its eyes pop-out?Why do your ears pop on an airplane or up in the mountains?
13The whole system is a low pressure, but it dramatically decreases towards the eye of the hurricane. Very Low pressurePressure always flows from high to low, which creates the high velocity winds.Higher Pressure
14Barometric Pressure The barometer is used to forecast weather. Decreasing barometer means stormy weather and an increasing barometer means warmer weather.
243. What is the total force of the right Piston? F=Pa= 2000N/m2 x 20m2 =40,000N20m.002m21. What is the pressure of the left piston?2. What is the pressure of the right Piston?P= F/a = 4/.002 = 2000Pa2000Pa
25Hydraulic BrakesThe hydraulic brake system of a car multiplies the force exerted on the brake pedal.
26The tendency or ability of an object to float. BuoyancyThe tendency or ability of an object to float.
27BuoyancyThe pressure on the bottom of a submerged object is greater than the pressure on the top. The result is a net force in the upward direction.
28Buoyant ForceThe upward force exerted by a fluid on a submerged or floating object.
29BuoyancyThe buoyant force works opposite the weight of an object.
30Archimedes’ principle: Buoyant Force on an object immersed in a liquid equals the weight of the liquid displaced and the weight of the object if it floats.
32Hmm! The crown seems lighter under water! Archimedes' PrincipleHmm! The crown seems lighter under water!The buoyant force on a submerged object is equal to the weight of the liquid displaced by the object. For water, with a density of one gram per cubic centimeter, this provides a convenient way to determine the volume of an irregularly shaped object and then to determine its density
33Density and buoyancy: An object that has a greater density than the fluid it is in, will sink. If its density is less than the fluid it will float.Density
34A solid block of steel sinks in water A solid block of steel sinks in water. A steel ship with the same mass floats on the surface.
35DensityChanges in density cause a submarine to dive, rise, or float.
36DensityChanges in density cause a submarine to dive, rise, or float.
37DensityChanges in density cause a submarine to dive, rise, or float.
45Bernoulli’s and Baseball A non-spinning baseball or a stationary baseball in an airstream exhibits symmetric flow. A baseball which is thrown with spin will curve because one side of the ball will experience a reduced pressure. This is commonly interpreted as an application of the Bernoulli principle. The roughness of the ball's surface and the laces on the ball are important! With a perfectly smooth ball you would not get enough interaction with the air.Bernoulli’s and Baseball
46Bernoulli’s and Air Foil The air across the top of a conventional airfoil experiences constricted flow lines and increased air speed relative to the wing. This causes a decrease in pressure on the top according to the Bernoulli equation and provides a lift force. Aerodynamicists (see Eastlake) use the Bernoulli model to correlate with pressure measurements made in wind tunnels, and assert that when pressure measurements are made at multiple locations around the airfoil and summed, they do agree reasonably with the observed lift.
48Others appeal to a model based on Newton's laws and assert that the main lift comes as a result of the angle of attack. Part of the Newton's law model of part of the lift force involves attachment of the boundary layer of air on the top of the wing with a resulting downwash of air behind the wing. If the wing gives the air a downward force, then by Newton's third law, the wing experiences a force in the opposite direction - a lift. While the "Bernoulli vs Newton" debate continues, Eastlake's position is that they are really equivalent, just different approaches to the same physical phenonenon. NASA has a nice aerodynamics site at which these issues are discussed.
52Liquid Pressure = ρgh where….. MORE EQUATIONS!!!Liquid Pressure = ρgh where…..ρ = mass/volume = fluid densityg = acceleration of gravity h =height or depth of fluid
53Fluid Pressure = gh = 1000Kg/m³ x 9.8m/s² x 1m = 9,800 Pa The pressure from the weight of a column of liquid of area A and height h isThe most remarkable thing about this expression is what it does not include. The fluid pressure at a given depth does not depend upon the total mass or total volume of the liquid. The above pressure expression is easy to see for the straight, unobstructed column, but not obvious for the cases of different geometry which are shown.Fluid Pressure = gh = 1000Kg/m³ x 9.8m/s² x 3m = 29,400 Pa