Question #2e05a

1 Answer
Mar 23, 2017

See below

Explanation:

Guessing that this is a classical physics question, well, they push against matter.

They use their wings to push air molecules in the direction opposite to the direction of their desired travel.

And as the bird's wings pushes air behind and below it, the molecules of air exert and equal and opposite force on the bird.

The main scientific principles are Newton's 2nd and 3rd Laws.