Flight

What are the four forces that affect a plane's ability to fly?

• Weight, lift, gravity, and thrust

• Weight, drag, lift, and thrust

• Gravity, drag, lift, and propulsion

• Weight, drag, gravity, and propulsion

Answer explanation

The four forces affecting a plane's ability to fly are weight, drag, lift, and thrust. Weight pulls the plane down, lift pushes it up, thrust propels it forward, and drag resists its motion. Thus, the correct answer is 'Weight, drag, lift, and thrust'.

Which force must be greater than or equal to weight for a plane to fly?

• Drag

• Thrust

• Lift

• Gravity

Answer explanation

Lift is the upward force generated by the wings of a plane. For a plane to take off and fly, lift must be greater than or equal to the weight of the plane, overcoming gravity.

What is the role of thrust in an airplane's flight?

• It pulls the plane upward.

• It moves the plane forward.

• It pushes the plane downward.

• It stabilizes the plane.

Answer explanation

Thrust is the force that propels an airplane forward. It is generated by the engines and is essential for overcoming drag and achieving flight. Therefore, the correct answer is that thrust moves the plane forward.

How does the shape of an airfoil contribute to lift?

• It increases the weight of the plane.

• It decreases the thrust needed.

• It causes air to move faster above the wing, creating lower pressure.

• It increases drag to stabilize the plane.

Answer explanation

The shape of an airfoil is designed to create a pressure difference. As air moves faster over the curved top surface, it reduces pressure above the wing, generating lift, which is essential for flight.

What is the function of ailerons on an airplane?

• To control the plane's speed

• To control the plane's altitude

• To control the plane's turns

• To control the plane's thrust

Answer explanation

Ailerons are control surfaces on the wings of an airplane that manage roll, allowing the aircraft to turn. They work by changing the lift on each wing, making them essential for maneuvering during flight.

Which part of the plane is responsible for controlling its climb and dive?

• Rudder

• Ailerons

• Elevators

• Propellers

Answer explanation

The elevators are the control surfaces located on the tail of the plane. They are responsible for controlling the pitch, which allows the aircraft to climb or dive. The other options do not perform this function.

What happens when the elevators on the tail of a plane are raised?

• The plane's nose tilts downward.

• The plane's nose tilts upward.

• The plane turns left.

• The plane turns right.

Answer explanation

When the elevators on the tail of a plane are raised, they create an upward force on the tail, causing the plane's nose to tilt upward. This is a fundamental principle of aircraft control.

How does a jet engine generate thrust?

• By flapping wings

• By sucking air in the front and spitting it out the back

• By rotating propellers

• By using a parachute

Answer explanation

A jet engine generates thrust by sucking air in through the front, compressing it, mixing it with fuel, and igniting the mixture. The high-speed exhaust gases are then expelled out the back, creating thrust according to Newton's third law.

What is the effect of drag on an airplane?

• It helps the plane to ascend.

• It resists the plane's forward motion.

• It increases the plane's speed.

• It stabilizes the plane's altitude.

Answer explanation

Drag is a force that opposes the forward motion of an airplane, making it harder for the plane to move through the air. Therefore, the correct answer is that drag resists the plane's forward motion.

Why is the airfoil shape important for reducing drag?

• It increases the plane's weight.

• It causes air molecules to stick close to its surface, streamlining the wing.

• It decreases the plane's lift.

• It increases the plane's thrust.

Answer explanation

The airfoil shape is crucial for reducing drag because it allows air molecules to flow smoothly over the wing's surface, minimizing turbulence and resistance, which streamlines the wing and enhances aerodynamic efficiency.