1. Forces and Pressure in Fluids
Forces in Fluids
Chapter 13 Section 2
Physical Science

2. Pressure in Fluids
In the last section, we learned a fluid exerts pressure equally in ALL directions at a given depth
This means that at the same depth the pressure is equal in all directions
The lower you go the more pressure
This is why a larger stream of water came out the bottom hole of the 2 liter

3. Pascal’s Principal Pascal’s Principal:
The forces on the walls in bottle A is equal at any given depth
Pascal’s Principal:
A change in pressure at any point in a fluid is transmitted equally in all directions
When squeezed, the pressure is transferred equally, not just where you squeeze

4. Hydraulic Systems
A hydraulic system uses pressurizes fluid acting on pistons of different sizes to change a force
Applies Pascal’s Principal

6. Bernoulli’s Principal
Swiss scientist Daniel Bernoulli discovered the reason why a sheet of paper rises when you hold the corners and blow over the top surface
Bernoulli’s Principal says that as the speed of a fluid increases, the pressure within the fluid decreases
From yesterday, the top of the paper has a decrease in pressure while the bottom of the paper has an increase in pressure causing the paper to rise

7. Bernoulli’s Principal
This also explains the ping pong ball on the hair dryer. The stream of air causes the ball to rise. The pressure in the air stream is lower than the surrounding air. If the ball moves out of the stream, it encounters high pressure and that forces the ball back into the low pressure air stream.

8. Bernoulli’s Principal
This also explains the devastating effects of a hurricane
The wind blows over the roof, creating low pressure. The difference in pressure of the house structure results in a strong upward force that can lift the roof off the house

9. Bernoulli’s Principal
This also explains the ability of birds and airplanes being able to fly
The air moves over the top of the wing faster than the bottom creating lower pressure on top
The high pressure under the wing causes it to rise
This upward force is known as lift

10. Bernoulli’s Principal
Wings can also create a downward force
This can be seen in a spoiler. It pushes the tires onto the road and gives the car better traction. Now you can take the corners at higher speeds

11. Bernoulli’s Principal
This concept can also be applied to spray bottles
The fast moving water from the hose creates low pressure. The pressure difference forces the solution up the tube. The solution mixes with the water and sprays out of the container