1. How do objects move in fluids?
Lesson 4
In this lesson: Students identify air as a fluid and demonstrate the effects of resistance and compression. They identify common applications of air when it is compressed, or when it is used for its insulating abilities.

2. MINDs ON Video Giant Smoke Ring
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3. Lesson vocabulary
Compress: squeeze together to make smaller or more compact.
Current: a flow or stream of water or air moving in one direction.
Perpendicular: at right angles to a given surface.
Pneumatic: a piece of technology operated by compressed air; worked by air pressure.

4. Lesson vocabulary (CONT’D)
Resistence: an opposing force.
Rudder: a hinged piece attached at the rear of a boat or aircraft, used for steering.
Turbulance: irregular movement of a fluid.

5. fluids description A fluid is any substance that flows easily.
Liquids and gases are both fluids.
Examples: water (liquid) and air (gas).

6. fluids characteristics of fluids
Fluids can change their form if a force or pressure is applied.
Gases are compressible, while liquids are less compressible.
All fluids resist the motion of objects travelling through them because those objects rub against the atoms and molecules that make up the fluid.

7. Compressed air straw through potato experiment
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The secret is inside the straw – it's air! Placing your thumb over the end of the straw traps the air inside. When you trap the air inside the straw, the air molecules compress and give the straw strength, which in turn keeps the sides from bending as you jam the straw through the potato. The trapped, compressed air makes the straw strong enough to cut through the skin, pass through the potato, and exit out the other side. Without your thumb covering the hole, the air is simply pushed out of the straw and the straw crumples and breaks as it hits the hard potato surface.  

8. Compressed air Description
Compressed air is air that is squeezed into a smaller space (put under greater pressure).
Compressed air exerts a greater force, which can be a useful property to utilize for many practical applications.
What types of devices use compressed air? Pneumatic.
Brainstorm pneumatic devices. Tire pump, scuba tanks, paint sprayers, etc.

9. Insulation description
Another useful property of air is its ability to insulate.
Insulation is the process of slowing down the movement of heat from where it is warm to where it is cold.
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