Pascal’s Principle Goal: Students will be able to explain Pascal’s principle

IV. Pascal’s Principle change in pressure in a trapped fluid will be transferred to all parts of the fluid. change in pressure in a trapped fluid will be transferred to all parts of the fluid. Fluids flow from areas of high pressure to areas of low pressure Fluids flow from areas of high pressure to areas of low pressure

Hydraulic systems How do brakes work? How do brakes work?

Hydraulic systems Liquids and gasses are both fluids BUT Liquids and gasses are both fluids BUT Gasses can be compressed, liquids cannot Gasses can be compressed, liquids cannot Pascal’s principle states that pressure applied to one part of a fluid is transferred equally to all parts Pascal’s principle states that pressure applied to one part of a fluid is transferred equally to all parts Hydraulic multiplication can greatly increase the pressure on the other end of the system Hydraulic multiplication can greatly increase the pressure on the other end of the system

Straws and siphons Why do they work? Why do they work? Straw: Straw: When you suck on a straw that is in a liquid the air at the top is removed When you suck on a straw that is in a liquid the air at the top is removed Since there is no air at the top of the straw, there is less pressure inside than outside Since there is no air at the top of the straw, there is less pressure inside than outside Pascal principle says fluids flow from high to low pressure Pascal principle says fluids flow from high to low pressure Therefore the liquid is pushed by pressure up the straw Therefore the liquid is pushed by pressure up the straw Siphon: Siphon: Same effect as a straw PLUS Same effect as a straw PLUS Gravity and the gravitational potential energy of the liquid keep it flowing Gravity and the gravitational potential energy of the liquid keep it flowing

V. Bernoulli’s Principle: 1. Bernoulli’s principle says as the speed of a moving fluid increases, its pressure decreases. (Fluid pressure increases as speed decreases.)

2. If air moves faster above the object, the fluid pressure pushes the object upward. If air moves faster below the object, the fluid pressure pushed it downward

III. Bernoulli’s Principle: 3. Faster moving air above a plane’s wing reduces the pressure, so increased pressure below the planes wing causes lift (an upward force

B. Lift 3.) Planes with greater thrust move faster and faster speed means greater lift. 3.) Planes with greater thrust move faster and faster speed means greater lift. 4.) In fluids, the force that opposes motion is drag. 4.) In fluids, the force that opposes motion is drag. 5.) Drag is usually caused by irregular flow of fluids known as turbulence. 5.) Drag is usually caused by irregular flow of fluids known as turbulence. 6.) When turbulence causes drag, lift is reduced. 6.) When turbulence causes drag, lift is reduced. 7.) Flaps are used to change the shape and area of a wing to reduce drag and increase lift. 7.) Flaps are used to change the shape and area of a wing to reduce drag and increase lift.