Air+and+Flight

Three demonstrations we did showed us different properties of air. 'Full Bag/Empty Bag' let us see (again) that air is made of matter and so it **has volume (takes up space).** 'CO2 and the Candle' showed the class that air moves like water. It **flows or moves like a fluid**. 'Heavy News' gave us a picture of the **pressure (force against) that air exert** on objects.
 * __Properties of Air__**

__**Bernoullli's Principle Activities**__ The four different activities we did in the lab let us see how: - faster (air) molecules exert lower pressure.** - also that in general, matter moves from high pressure to low pressure (we will see this again in our study of weather).
 * - objects move toward faster moving air.

We also discussed the difference between direct and indirect pressure. - We defined __direct pressure__ as when **the direction of the force is the __same__ as the direction of the objects movement**. - We defined __indirect pressure__ as **when the direction of the force is __different__ from the direction of the objects movement**. media type="file" key="Wings_Provide_Lift.mov"

__**Four Forces of Flight**__ The four forces of flight are: - __Gravity/Weight__ provided by the Earth's pulll downward on all objects on the planet. - __Lift__ is the force pushing upward produced by the AIRFOIL shape of the wing. (Note the AIRFOIL is a streamline shape which makes the **air going over the wing travel faster (making less pressure) than the air under the wing (maintaining higher pressure)**. - __Thrust__ is forward force provided by the propeller or engines. - __Drag__ is the force pushing the aircraft backward which is produced by air resistent. media type="file" key="The_Four_Forces_of_Flight__Gravity__Lift__Drag__and_Thrust.mov"

__**Balanced vs. Unbalanced Forces**__ __Balanced forces__ are when opposing forces are **equal** in strength. This produces no overall motion (the object **stops**). __Unbalanced forces__ are when opposing forces are **unequal** in strength. This produces **movement in the direction of the stronger force.**