How planes aviate?

     You know that gravity pulls on all things on Earth's surface.
     How can birds and planes fly?What kind of forces they use?

Why planes aviate?

1. Fold a plane and throw it.

3-5-7-1.jpg (44918 bytes)

Gravity pulls it down.
The verve you gave it moves it onwards.
Air's friction retards the plain
Air pressure prevents it falling down.

2. Draw arrows .What forces push and pull the plain and where they affect.
3. What forces hold the plain in the air?
..............................................................................................
4. What forces prevent falling down?
..............................................................................................

Fold different planes and look what kind of planes are better flyers.