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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.

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Presentation on theme: "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."— Presentation transcript:

1 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. Force Pressure greater Force Pressure less

2 Units of pressure are Newtons/meter 2 1 N/m 2 = 1 pascal (Pa)

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

4 Cartesian Diver Pressure increased Pressure decreased

5 Fluid Particles 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.

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

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

8 Air and water pressures press on objects from every direction.

9 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.

10 As your elevation increases, atmospheric pressure decreases. Water pressure increases as depth increases.

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

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

13 The buoyant force acting on the object equals the weight of the water displaced by the object.

14 Weight Buoyant Force Weight Buoyant Force

15 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.

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

17 10N Force 1m 2 area Pressure of 10N/m 2 100N Force 10m 2 area Pressure = 10N 1m 2 Force = 10N/m 2 x 10m 2

18 How much pressure is produced by a 150N force acting over an area of 3m 2 ? A 5N force is applied to a 5m 2 piston in a hydraulic device. If the second piston has an area of 25m 2, what is the force produced by this second piston? PressureForceArea ?300N20m 2 15N/m 2 ?15m 2 3,000N/m 2 150N? ?750N7.5m 2

19 The faster a fluid moves the less pressure the fluid exerts. As the speed of a moving fluid increases, the pressure within the fluid decreases.

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

21 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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