How The Forces In Fluids Allow Heavy Airplanes

508 Words2 Pages

Write an expository essay explaining how the forces in fluids allow heavy airplanes to fly.

• Bernoulli's principle
• wing shape
• lift
• thrust
• drag

Every object on Earth has weight, a product of both gravity and mass. A Boeing 747-8 passenger airliner has a maximum takeoff weight of 487.5 tons (442 metric tons), the force of the weighty plane is drawn toward the Earth. Weight's opposing force is lift, which holds an airplane in the air. This feat is accomplished through the use of a wing, also known as an airfoil. Like drag, lift can exist only in the presence of a moving fluid. It doesn't matter if the object is stationary and the fluid is moving (like with a kite on a windy day), or if the fluid is still and the object is moving through it. What really matters is the difference in speeds between the object and the fluid. …show more content…

(Gravity provides the thrust for a glider.) The engines push air back with the same force that the air moves the plane forward; this thrust force-pair is always equal and opposite according to Newton's 3rd Law.

Drag opposes thrust. Imagine sticking your hand out the window of a moving car and flying your hand. The force that pushes your hand back is called "drag". As your hand pushes on the wind, the wind also pushes against your hand. Isaac Newton would say that force of your hand pushing on the air is always equal to the force of the air pushing on your hand; this is his third law.

Lift opposes weight. Newton's Laws and Bernoulli's Principle generate lift. A plane that sits on a runway doesn't have any lift, but it does have weight. Lift is proportional to the square of the velocity of an airplane and as a plane goes faster, its lift increases. As a plane moves forward, its lift force increases until it equals its weight. When lift equals weight, the plane can fly. In level flight, lift equals weight as the plane flies at constant

More about How The Forces In Fluids Allow Heavy Airplanes

Open Document