 # Pressure Pressure is a force exerted over an area on the surface

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Pressure Pressure is a force exerted over an area on the surface
of an object. Force and Pressure are not the same thing: Pressure decreases as the area over which a force is applied increases. Pressure less Force Force Pressure greater

Pressure = Force Area Units of pressure are Newtons/meter2
1 N/m2 = 1 pascal (Pa)

Pascal's Principle Force Force When a force is applied to a confined fluid, the change in pressure is transmitted equally to all parts of the fluid.

Cartesian Diver Pressure increased Pressure decreased

Pressure is caused by the movement of particles
in the fluid. Every time they bump against the side of the container they create pressure. The more bumps the more pressure. Fluid Particles

The more particles, the more pressure. The
faster the particles move, the more pressure. Fluid Particles

Air Pressure Water Pressure
Pressure caused by the weight of the air in the atmosphere as gravity pulls it down toward the center of the earth. Water Pressure Pressure caused by the weight of water as gravity pulls it down toward the center of the earth. Remember, weight is a force.

Balanced Pressure Air and water pressures press on objects from every direction.

If the pressure becomes unbalanced, the pressure of air
or water can crush an object. The air pressure inside balances the air pressure outside the container. But if we take the air out of the container, the outside pressure will be far greater than inside and crush the can.

Atmospheric Pressure and Elevation
As your elevation increases, atmospheric pressure decreases. Water Pressure and Depth Water pressure increases as depth increases.

Buoyancy The force in liquids that acts opposite to gravity—it
causes objects to feel lighter. Objects sink if their weight is greater than the buoyant force acting on them.

Archimedes' Principle The buoyant force acting on a
submerged object is equal to the weight of the fluid the object displaces.

Archimedes' Principle The buoyant force acting on the object
equals the weight of the water displaced by the object.

Weight Weight Buoyant Force Buoyant Force

DENSITY Density = Mass Volume
If the density of an object is less than the density of water, the object will float. If the density of an object is greater than the density of water, the object will sink.

Pascal's Principle Force Force When a force is applied to a confined fluid, the change in pressure is transmitted equally to all parts of the fluid.

Hydraulic Systems Pressure of 10N/m2 Force = 10N/m2 x 10m2 100N Force
10m2 area 1m2 area Pressure = 10N 1m2 Pressure of 10N/m2

Pressure Force Area ? 300N 20m2 15N/m2 15m2 3,000N/m2 150N 750N 7.5m2
How much pressure is produced by a 150N force acting over an area of 3m2? A 5N force is applied to a 5m2 piston in a hydraulic device. If the second piston has an area of 25m2, what is the force produced by this second piston? Pressure Force Area ? 300N 20m2 15N/m2 15m2 3,000N/m2 150N 750N 7.5m2

Bernoulli's Principle so... The faster a fluid moves
the less pressure the fluid exerts. so... As the speed of a moving fluid increases, the pressure within the fluid decreases.

Moving stream of wind (fluid) Smoke moves up chimney from high to
Lower Pressure Moving stream of wind (fluid) Smoke moves up chimney from high to low pressure.

Wings are shaped so that air moves
faster over the top of the wing than under the wing. This causes lower pressure above the wing than below and creates lift so the plane can fly.

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