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# Science Exam Reveiw

TermDefinition
Fluid Any material that can flow and takes the shape of its container
All fluids exert _______ Pressure
Fluids can also be _____ Gases
Pressure The amount of force exerted on a given area
Pressure = (math) Force / area
SI Unit for pressure pascal (Pa)
Atmospheric The layer of nitrogen, oxygen and other gases that surround the earth
Atmospheric Pressure The pressure caused by the weight of the atmosphere
There are __N (_lbs) of pressure on every ______ _________ of your body 10N (2lbs); square centimeter
Which direction do the fluids in your body exert pressure in? The fluids exert pressure outward
How far does the Earth's atmosphere stretch? About 150km above the Earth
__% of the Earth's gases are found within the first __km of the atmosphere 80%; 10km
At the top of the atmosphere pressure is almost ___________, pressure is close to _Pa nonexistent; 0Pa
Water pressure _________ as depth _________ Increases; increases
Pressure depends on the _____ not on the total amount of fluid Depth
Water is 1000 times more _____ than air Dense
Density The amount of matter in a given volume
Fluids flow from areas of ____ pressure to areas of ___ preessure High pressure; low pressure
Buoyant Force The upward force that fluids exert on all matter
Pressure _________ as depth _________ Increases; increases
Water exerts a ___ ______ force (buoyant force) Net upward
Archimedes was... Greek mathematician in the 3rd century
Archimedes Principle States that buoyant force on an object in a fluid is an upward force equal to the weight of the fluid that the object takes the place of or displaces
An object will ____ if its weight is greater than the buoyant force Sink
An object will _____ if the buoyant force on the object is equal or more than equal to the objects weight Float
Floating and Sinking Density = (math) 1m = 1cm cubed - 5L of water = 5000cm cubed
Density = (math) Mass / volume
FInd the density of a rock that has a mass of 10g and a volume of 2cm cubed 5gcm cubed
How does a ship made of steel float if steel is denser than water? - Ships are built with a hollow shape - Same amount of steel bu the hollow shape increases the volume of the ship - Overall density is less than the density of the water
Why are ships built to displace more water than needed? Bc there are people and luggage on the boat (extra weight other than the ship)
What are ballast tanks and what do they do? - Tanks in a submarine that allow it to float/sink - When they open water flows in, making it its mass increase (volume stays the same) - When closed, they pump air in, making it less dense (allowing it to float)
What is a swim bladder and what does it do? - Swim bladder on a fish - It fills with gases (increasing volume, decreasing overall density) - It keeps the fish from sinking
Daniel Bernoulli Swiss mathematician in the 18th century
Bernoulli Principle States that as the speed of a moving liquid increases, the fluid pressure decreases
How do planes fly? Fast moving air above the wing exerts less pressure than slow moving air below the wing
The speed of a plane is mostly determined by its: Thrust and Larger thrust
Thrust Forward force that produces by the planes engine
Larger Thrust Increases speed, air travels around the wing at a higher speed which increases lift
Drag A force that opposes or restricts motion in a fluid
Turbulence An irregular or unpredictable flow of fluids
How do you determine the speed of air crafts? Calculate the drag in combination with thrust
____ is often reduced when turbulence causes drag Lift
Planes use their flaps to change the shape of the area of the wing to reduce ____ and increase ____ Reduce drag; increases lift
Blaise Pascal French scientist in the 17th century
Pascal Principle States that a change in pressure in an enclosed fluid will be transmitted equally to all parts of that fluid
Work A force that causes an object to move in the direction of the force
For work to be done on an object, the object must move in the ____ direction as the force Same direction
Work = (math) Force x Distance
Power The rate at which energy is transferred
Power = (math) Work / Time = Joules
Power measures what? How fast work happens or how quickly energy is transferred
Increase work, _________ power Increase
Decrease work, ________ power Decrease
Machine A device that makes work easier by changing the size ro direction of a force
Work is done when a force is applied through a ________ Distance
Work input The work you do on a machine
Work output Work done by the machine on an object