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Science Sheet of Objectives Ch. 11

1)Be able to define pressure mathematically and state the

units it is measured in. Be able to define a Pascal.Pressure is the force exerted over on area on the surfaceof an object more simply Pressure= force/area. Pressure ismeasured in pascals. This si unit takes the name from theFrench mathematischian blace pascal who discovered howpressure is transmitted in a fluid. More exactly a pascal isequivalent to Pascal = One Newton per square meter(1n/1meter 2)

2)Be able to explain how pressure works using a practicalexample (such as snowshoes).Force and pressure are closely related. Pressure increasesas Area decreseas: The larger the are a force is distributedthe smaller the pressure. For example: if you stand onsnow with your every day snekers you exert pressure onboth soles. The Area under the soles usually whenstanding in snow is not enogh to keeep you up becausethe bothe measure about 500 cm 2 in area and so you sink

but fi you put on snow shoes with a greater area such as1100 cm 2 you are morelikely if your weight (or the forceyou exerton the ground isnt execcive) to flot above thesnow. + Example of tacchi a spillo

3)Be able to describe fluid pressure and how it varies withelevation and depth.

A fluid is a material that can easily flow. In the phases ofmatter it is the phase between gas and solid.Fluids are madeup of particles that constatnatly collide together and withother surfaces. The combination of all the forces exserted bythe singleparticles makes up fluid pressure. Fluid pressure =Total force exerted by the combind particles that make u thefluid divided by the are over which its exerted.Air pressure = weight of the air created (the weight ) by theforce of gravityBalanced Pressure:Why arent we destroyed or crusged by the huge

atmospheric pressure that lies around us? Well the reasonfor life on earth resides inside balanced pressure. Thepressure in the atmosphere is everywhere so as you are

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pushed down by pressure the same pressure pushs you upso cancelling out itself. As for the same thing is why dont wecollapsebecause of ths tremendous pressure pushing us onall sides. Well the answer is that within us there are some

fluids which balance out the air pressure around us as waterin a bottle . as you pull away the air in a bottle it collapses .the same is for us air and other fluids that inhabit us balanceout the Atmospheric pressure that otherwise would crush us.As you change position in respect to the earth pressurechanges: As elevation increases atmospheric pressuredecreases ( sketch with plane, Mt. everest helicopter andskydiver plus sea level scuba diver , fish and submarine)

Water Pressure and Depth:Fluid pressure depnds on depthAsyou descend in any fluid (Ex: water and diving) pressureincreases because of the direct proportionality : waterpressure icreases as dpth increases.

4)Be able to state Pascals Principle and briefly explain whatit means using a practical example.

When force is applied on a confined fluid the changepressure is transmitted equally throughout (to all parts) the

fluid. This relationship between pressur e and fluids isknown as pascals principalEx: If you squeeze a bottle the pressure is thebaottlechanges in the ame way o top on the bottom from leftto right ( sketch)

Say something on brakes of a car and how they work largerarea/ larger force

5)Be able to state Archimedes Principal and explain how itworks using a practical example.

Archimedes princial is a rule explaning Buoyancy: the abilityto float. This principe states that the buoyant force acting ona submerged object its equivalent to the weight of the fluidthe object displaces. Fro example : Why do ships fload? Wellthey float because the buoyant force acting on them isgreater than the force pulling them down Take

twoobjects that weight the same amount for example a shipand a block of solid steel. The ship floats because the form of

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its hullcauses the ship to diplace great quantities of water.Instead the stells sinks because the water it diplaces is notenogh to keep up with his weight.So since the ship displacesmore water than the steel a grater buoyant force acts on the

ship and as Archimedes principal states the buoyant force =the weight of the fluid displaced by a suberged object.Archimedes principal helps explin why submarines float andsinkand many other things. ( a ship floats because itscomplexive density so weight is less than or equal to theweight of the water diplaced by a suberged ship-Density mass per unit of volume (D=m/v)Changing density ( submarine Ex)Be able to state Bernoullis Principle and explain how it works using a

practical example.Bernoullis principal has made it possible for humans too fly.As the speed within a moving fluid decreases the pressure within itdecreases