NEET BIOLOGY

Detailed explanation-1: -Birds use their wings to generate two forces, lift and thrust, with which they overcome gravity and drag. There are four forces acting on a bird in flight, lift, thrust, drag and gravity (weight).

Detailed explanation-2: -It’s a misconception if one thinks flying birds are not pulled by Earth’s gravity. Every object on Earth is influenced by gravity. Even the Earth is influenced by the Sun’s gravity.So, if birds fly, they are doing so despite the gravitational pull, through their aerofoil structure.

Detailed explanation-3: -Birds fly by flapping their wings. Flight involves moving upward, against the force of gravity, and forward too. The power for this comes when the massive chest muscles pull the wings down. These muscles are 10 times bigger than the muscles that pull the wings back up.

Detailed explanation-4: -Bird’s flight consists of two main movements. They are upstroke and down stroke. When the wings move upwards, the movement of the wings is called upstroke movement. When the wings move downwards, the movement of the wings is called down stroke movement.