Pascals and Bernoullis Principle Physics Kena Allison What

Pascal’s and Bernoulli’s Principle Physics Kena Allison

What does Pascal’s principle state? • A change in pressure at any point in an enclosed fluid at rest is transmitted without loss, to all points in the fluid

Figure 13. 21 • What is the picture trying to explain? The force applied to an area (Pressure) on the left is applied to the same area on the right to keep the same pressure on both sides.

Figure 13. 22 • Pressure stays the same on both sides BUT the forces get multiplied on the right because the area is twice as great as the left.

What technology uses Pascal’s principle? • Hydraulic pumps and other devices – Construction machines – Car hydraulics – Car lifts

How did the demonstration with the syringes explain Pascal’s principle? • Easy to apply force to the small syringe to lift the large syringe • BECAUSE- the small force was multiplied equally into each area of the larger syringe

What does Bernoulli’s principle state? • When the speed of a fluid increases, the internal pressure in the fluid decreases

• What happens to the paper when you blow across the top? – Paper rises • Why? – Breath speeds air molecules which decrease pressure on top of paper – The pressure under the paper pushes the paper up

Inverted Umbrella • Use Bernoulli’s principle to explain why your umbrella inverts on a windy day. – Wind blows on top of umbrella – Air molecules speed up on top of umbrella; therefore, pressure decreases on top of umbrella – Air under umbrella which has greater pressure pushes up and inverts umbrella

Shower Curtain • Use Bernoulli’s principle to explain why your shower curtain blows inward with a hot shower. – Hot inside shower – Air molecules speed up inside shower; therefore, pressure decreases inside shower – Air outside shower with more pressure pushes shower curtain in

Another Example • What could you do to get the ping pong balls to move toward each other? – Increase speed of air between the ping pong balls – This would decrease the pressure – Air outside ping balls would have more pressure and push them toward each other