FISIKA KELAS XI - GAYA ANGKAT PESAWAT TERBANG || FLUIDA DINAMIS

Summary

In this video, Yusuf Ahmad explains the concept of aircraft lift, focusing on how airspeed differences over and under the wings create pressure variations that enable an aircraft to fly. The video discusses the key conditions for lift, how it changes during takeoff, steady flight, and landing, and provides the formula for calculating lift force. Examples are given, demonstrating how to apply the formula to calculate the lift generated by an aircraft based on airspeed and wing area. This informative explanation is ideal for anyone looking to understand the fundamental principles of flight dynamics.

Takeaways

• 😀 The video explains the concept of 'lift force' that allows airplanes to fly, specifically focusing on how the shape of an airplane's wings generates this force.
• 😀 The wings of an airplane are designed with a thicker front and a thinner back, creating different airspeeds above and below the wings, which is essential for lift.
• 😀 For an airplane to take off or stay in the air, the pressure beneath the wings must be greater than the pressure above the wings.
• 😀 The airspeed above the wings must be faster than the airspeed below the wings to create the necessary difference in pressure (Bernoulli's principle).
• 😀 When an airplane is ascending, the lift force must exceed the aircraft's weight to initiate takeoff.
• 😀 In level flight (cruising), the lift force equals the weight of the airplane to maintain stable altitude.
• 😀 During landing, the lift force is intentionally reduced to be smaller than the airplane's weight to bring the plane down.
• 😀 The formula for calculating lift is: F_L = 1/2 * ρ * (V_a^2 - V_b^2) * A, where ρ is air density, V_a and V_b are airspeeds above and below the wings, and A is the wing area.
• 😀 An example is provided where a plane's wing area is 80 m², with airflow speeds of 250 m/s above and 200 m/s below the wings. The result is a lift force of 108,000 N or 108 kN.
• 😀 Another example demonstrates how to calculate the required airspeed above the wings if the lift force is known, with given airspeed below the wings and wing area, resulting in a needed airspeed of 300 m/s above the wings.
• 😀 The video encourages viewers to subscribe for more educational content on physics, thanking them for their support and engagement.

Q & A

What is the concept of lift on an airplane?

Lift is the upward force that allows an airplane to become airborne. It is generated by the pressure difference between the upper and lower surfaces of the aircraft's wings.

Why do the speeds of air above and below the wing differ to create lift?

The speed of the air above the wing must be greater than the speed of the air below it to create a pressure difference. According to Bernoulli's principle, faster air results in lower pressure, helping lift the airplane.

How does the design of an airplane's wing contribute to generating lift?

An airplane wing is designed with a curved upper surface and a flatter lower surface, which causes air to flow faster over the top, creating a lower pressure above the wing compared to the higher pressure below it.

What is the formula for calculating lift on an airplane?

The formula for calculating lift (Fa) is: Fa = 1/2 * ρ * (V_a^2 - V_b^2) * A, where ρ is the air density, V_a is the velocity of air above the wing, V_b is the velocity of air below the wing, and A is the area of the wing.

How does the velocity of air affect the lift on an airplane?

The velocity of air above the wing must be higher than below the wing to generate the required pressure difference. This difference in velocity creates a higher pressure below the wing, leading to lift.

What is the role of air density in the calculation of lift?

Air density (ρ) directly influences the amount of lift generated. Higher air density results in greater lift, as the force is proportional to the density of the air.

What happens to lift when an airplane is taking off?

During takeoff, the lift must be greater than the weight of the airplane to overcome gravity and allow the plane to ascend into the air.

How does lift balance with the airplane’s weight when cruising at constant altitude?

At a constant cruising altitude, the lift equals the weight of the airplane. This balance ensures that the airplane remains at a stable altitude without rising or descending.

Why is the area of the airplane's wings important in generating lift?

The area of the wings (A) is crucial because a larger wing area allows for more air to be displaced, resulting in a higher lift force. This is why aircraft with larger wings can carry heavier loads.

How do the pressures above and below the wing change during landing?

During landing, the lift must be reduced to be less than the airplane's weight, allowing it to descend safely. This is achieved by decreasing the speed of air over the wings or altering the wing's angle of attack.