Newton’s Third Law of Motion states that for every action, there is an equal and opposite reaction. When a bird flaps its wings, it pushes air downwards. According to Newton’s Third Law, the air pushes back on the bird with an equal force in the opposite direction, which is upwards.
This upward force helps the bird to stay aloft. However, the bird’s wings are not just moving up and down; they are also moving forward and backward. As the wings move forward, they push air backward, and again, according to Newton’s Third Law, the air pushes the bird forward with an equal force.
This forward force propels the bird through the air, allowing it to fly forward. The combination of these forces—upward lift and forward thrust—enables the bird to maintain level flight. The bird continuously adjusts the angle and speed of its wing flaps to control its direction and speed, ensuring smooth and efficient flight.