How Do Planes Fly?

    Its a plane, an object what can weigh up to 500tons. How can a giant piece of metal fly and stay up in the sky? For a plane to stay in flight it needs four forces to work together. Thrust, lift, weight or gravity and drag. Thrust is what keeps the plane moving forward. Depending on the plane there are different methods to produce thrust. Jets will use its jet engine while other planes such as a crop duster will use a propeller.

    Lift is what keeps the plane up and is one of the reasons why a plane has wings shaped the way they are. Many plane's wings are curved at the top and smoother at the bottom. This allows the air passing over the wing to move faster which decreases the air pressure since the air pressure above the wing is lower than the air pressure below the wing. It causes the plane to lift.

    Drag is the force that slows the plane down. You've probably experienced drag when you had to walk against the strong wind or have gone skiing down a hill. For a plane to stay in flight it must have stronger lift than drag similar to how the wings help with increasing lift,the shape of the wings will also help with decreasing drag.

    Weight is caused by gravity and is what forces the plane down. The plane is designed the way it is to distribute the weight evenly throughout rather than concentrated in specific areas. When all four forces are working together this causes the plane to fly lift and weight work together to move the plane up and down, while thrust and drag work together to speed and slow the plane down.

    Lastly you should always have a pilot just like a captain steers a ship the pilot steers the plane to its final destination so that answer how the planes fly.

source: Thinking Captain https://youtu.be/wFTHh-6jIT8

What is the main idea of the fourth paragraph?