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Forces in Fluids

Forces in Fluids . Principles of Chemistry and Physics Mrs Sedlock. PRESSURE. Pressure. Which would hurt more, a 150 lb person stepping on your foot wearing a sneaker, or a 150 lb person wearing a high heeled shoe?

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Forces in Fluids

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  1. Forces in Fluids Principles of Chemistry and Physics MrsSedlock

  2. PRESSURE

  3. Pressure Which would hurt more, a 150 lb person stepping on your foot wearing a sneaker, or a 150 lb person wearing a high heeled shoe? In each case the weight (applied force) is the same, but the area is smaller, so the pressure will be greater and hurt more Why do you chop wood with an axe and not a hammer?

  4. Pressure • Pressure - the amount of force in an area. • Pressure = force area PRESSURE AND FORCE ARE NOT THE SAME!!

  5. Pressure Force is often measured in Newtons (N) Pressure is measured in Pascals (Pa) this is a very small amount so sometimes measured in kiloPascals (kPa)

  6. Pressure Ex: A box with a weight of 2700 Newtons is resting on the ground. If the area of the box touching the ground is 1.5 square meters, what pressure does the box exert on the ground? 1.8 kPa

  7. Pressure Ex: A box with a weight of 2700 Newtons is resting on the ground. The box is balancing on the edge, the area of the box touching the ground is 0.50 square meters, what pressure does the box exert on the ground? 5.4 kPa

  8. Pressure • What keeps a balloon inflated? • Pressure • Countless “air” particles colliding with the sides of the balloon. • Name three ways to inflate the balloon further? • Increase the amount of matter in the balloon (blow more “air” into it. • Increase the amount of collisions on the inside of the balloon by increasing the temperature on the balloon. • Decrease the amount of pressure on the balloon.

  9. Fluid Pressure

  10. Pressure in Fluids • Fluid- a substance that assumes the shape of its container • Liquids • Gases

  11. Pressure in Fluids Water pressure INCREASES as depth INCREASES The pressure in a fluid at any given depth is constant and it is exerted equally in all directions

  12. Pressure in Fluids Water bottle demo

  13. The shape of the container does not affect fluid pressure

  14. Pressure in Fluids Depth and type of fluid are the only two factors that determine the pressure the fluid exerts

  15. Fluid Pressure

  16. Air Pressure

  17. Layers of the Atmosphere

  18. Air Pressure Air pressure decreases as you move farther from the surface of the earth

  19. Air Pressure Air pressure exerts about 1000 newtons of force on top of your head

  20. Pressure in a Fluid • Atmospheric pressure at sea level is caused by a large weight of gas, but is difficult to notice because there is an equal, internal pressure pushing out from the inside of your body.

  21. Buoyancy

  22. Buoyant Force Buoyancy – the ability of a fluid to exert an upward force on an object placed in it Demo – Law of Conservation of Mass

  23. Buoyant Force • Buoyancy results in the apparent loss of weight of an object in a fluid • When an object is placed in water, the water exerts an upward force on the object – makes it easier to lift

  24. Equal!

  25. Buoyant Force When the buoyant force is equal to the weight, an object floats, or is suspended When the buoyant force is less than the weight of the object, the object sinks how submarines work

  26. Archimedes Principle Archimedes principle- the buoyant force on an object is equal to the weight of the fluid displaced by the object

  27. Buoyant Force Why does a piece of steel sink but a steel ship floats? how ships float

  28. Buoyant Force • An object that has the same density as the fluid it is submerged in will be suspended • Submarines • Fish

  29. Buoyant Force The more dense the liquid is, the greater the weight of the displaced liquid, easier for heavier objects to float Easier to float in very salty water

  30. Pressure in a Fluid

  31. Forces and Pressure Pascal’s Principle- a change in pressure at any point in a fluid is transmitted equally and unchanged in all directions throughout the fluid

  32. Hydraulic Systems Hydraulic system uses pressurized fluid acting on pistons of different sizes to change a force

  33. Forces and Pressure Have you ever wondered how a little energy from your foot pressing on the brake pedal in your car can bring a 1 ton car to a stop? Through leverage and Pascal’s Principle

  34. Brake pedal transmits the brake fluid through the master cylinder which stores the brake fluid – forces fluid out to the brake’s wheels which causes the clamp action of a disc brake

  35. Bernoulli’s Principle As the speed of a fluid increases, the pressure within the fluid decreases bernoulli demo

  36. Bernoulli’s Principle

  37. Bernoulli’s Principle

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