IELTS READING LEVEL 6.5 – How Do Airplanes Fly?

How Do Airplanes Fly?

by Dr. Hany Farid

When an airplane is in flight, there is a downward force (gravity) and an upward force (lift) acting on the airplane. As an airplane moves through the air, the shape of the wings causes there to be less air pressure pushing down on the wings than pushing up on the wings. This difference in pressure yields the upward lift. If the downward gravitational force is less than the upward lift, then the airplane stays in the air. Read on for a more detailed explanation.

Fact 1. As an airplane’s propellers spin, they give the airplane a forward force (thrust). As the airplane moves forward there is a backward force (drag) caused by the resistance of the air.

Fact 2. An airplane is attracted downward due to gravity. This force increases with the mass (weight) of the object.

Fact 3. As an airplane moves forward, the shape of its wing creates lower pressure above the wing than below, yielding a net upward force known as lift.

As an airplane speeds along the runway, the airplane’s wings disrupt the flow of the air. This disruption causes the air above the wings to move faster than below the wings. As a result, the air pressure above the wing is less than below the wing. As the airplane speeds up, this pressure difference increases until the lift is stronger than the gravitational force, and the airplane takes off. In order to remain in flight, the thrust must be greater than the drag, and lift must be greater than the force of gravity.

There is still some debate as to the exact cause of the difference in the air’s speed around the wings. The basic concept described here, however, seems to explain why an airplane can fly.

Vocabulary

disrupt       dis ·rupt

Advanced Definition

transitive verb

1. to throw into disorder or turmoil.

An explosion disrupted the peaceful demonstration.

2. to interrupt or break off, usually temporarily.

Hecklers disrupted the governor’s speech.

These are some examples of how the word or forms of the word are used:

1. Those substances can disrupt the body’s hormone balance.
2. Kidney stones cause pain when they disrupt urine flow (which can cause infection).
3. The entire class listened to their teacher in silence, afraid to disrupt the atmosphere of the ancient temple.
4. Recent studies show that chemicals called phthalates, which may disrupt hormones, can seep into bottled water from the plastic container.
5. That’s why we must always be careful to take care of the environment-the earth’s temperature is carefully maintained by specific mechanisms. We sure wouldn’t want todisrupt them!

force       force

Definition

noun

1. power, energy, or physical strength.

The force of the wind knocked down the trees.

2. a group of people with a common goal or activity.

She is a member of the police force.

verb

1. to make or cause to do something by using strength or power.

Ivan forced her to tell the truth.

Advanced Definition

noun

1. active power, energy, or physical strength.

The force of the hurricane knocked down the trees.

2. the use of such power, energy, or strength.

The enemy took the castle by force.

3. someone or something with the capacity to influence or cause change.

The force of logic eventually convinced the committee.

A group of parents was the main force behind the change in the town’s speed limit.

She believed that, as a politician, she could be a force for good.

4. in law, illegal violence, as against a person.

Accidental death was ruled out, as use of force on the victim was apparent.

5. a group of people joined by a common goal or activity.

the labor force

the police force

6. in physics, an influence on the shape, motion, or other characteristics of a body or system.
7. (often pl.) military troops; army.

The enemy has overpowered our forces in the area.

8. effective intensity, as of the mind.

transitive verb

1. to use strength or coercion in order to compel.

The interrogators forced him to tell the truth.

2. to cause to do something despite resistance or hesitation.

The accident forced her to rely on her family for help.

Being turned down for promotion forced him to make a difficult decision.

3. to bring about (something) despite there being reluctance or unwillingness.

The scandal forced the congressman’s resignation from office.

Complaints from customers forced the removal of the product from the market.

4. to obtain through force.

His captors forced a confession from him.

5. to tax or strain.

Don’t force the situation.

These are some examples of how the word or forms of the word are used:

1. Darwin realized that the birds had grown beaks specialized for their environment because nature had forced them (to) over many generations.
2. In an actual launch, astronauts feel about three times the force of gravity. Gravity is the force that pulls things toward Earth.
3. Electromagnetic force is the interaction responsible for almost everything in daily life. Magnets are objects that produce an area of magnetic force called a magnetic field.
4. Mom grabbed the end of one, and I held the handle on the other; and we yanked. The buckets slid free, and I fell over from the force of the pull.
5. Kinetic energy is a term related to physics that describes the energy an object possesses due to motion. Measuring an object’s kinetic energy means measuring the amount oforce an object needs to accelerate.
6. There is a vitality, a life force, an energy, a quickening that is translated through you into action, and because there is only one of you in all of time, this expression is unique.