# WHAT HAVE WE SEEN SO FAR? A brief recap…. So far, we have looked at fluids and we have seen that fluids exist as both liquid and as air. FLUIDS We have.

## Presentation on theme: "WHAT HAVE WE SEEN SO FAR? A brief recap…. So far, we have looked at fluids and we have seen that fluids exist as both liquid and as air. FLUIDS We have."— Presentation transcript:

WHAT HAVE WE SEEN SO FAR? A brief recap…

So far, we have looked at fluids and we have seen that fluids exist as both liquid and as air. FLUIDS We have also seen how a fluid passes around an object.

Bernoulli noticed that pressure exists all around us. In fact, he found that stationary fluids such as air and water exert pressure in all directions. BERNOULLI’S PRINCIPLE

Bernoulli also discovered that the faster air flows, the less pressure it has.

Now, we are going to look at the force of LIFT and see how it applies to flying objects such as airplanes.

FLYING WINGS

Airplanes stay in the air because of the shape of their wings.

Imagine a wing without it’s skin on

Imagine a wing flying fast through the air DIRECTION OF AIRPLANE

The special shape of a wing is called an airfoil.

An airfoil is flat on the bottom and curved on the top. BOTTOM TOP

BOTTOM DIRECTION OF AIRPLANE

How does a wing rise as air passes around it?

When air hits the front of the wing it splits up

The air flowing over the curved top of the wing has further to go than the air going under the flat bottom of the wing.

Predict: How will both air molecules arrive at the tail of the wing at the same time if the molecule on top has a farther distance to travel?

For the two streams of air to reach the back of the wing at the same time, the top stream must travel faster than the bottom. (It has a farther distance to go.)

This fast moving air creates a low pressure area on the top of the wing and a high pressure area on the bottom of the wing. (Bernoulli’s Principle) LOW PRESSURE HIGH PRESSURE

Predict: What is our high pressure air zone going to do? Why? LOW PRESSURE HIGH PRESSURE

Air will move from a high pressure zone to low pressure zone. As it pushes against the wing, lift is created. LOW PRESSURE HIGH PRESSURE

UP

AND

AWAY!!!

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