Category: Physics Notes PPT

According to acoustics, a beat is an interference pattern between two sound waves of different sound frequencies or a periodical variation in volume. Here, both the waves should travel in the same direction.  The beat frequency is common in the tunning instruments, this will produce sustained beats, tones and they can readily be recognized. While tuning two tones to a unison will shows a peculiar effect. When the two sound waves, which are not identical are close in pitch will generate the beating. The volume of beats is varied like a tremolo as the sounds interfere are constructive and destructive.  When the tones gradually reach unison, the beats get slow down. If the two tones are separated, their beat frequency will approach the human pitch range perception. 

Beats are produced when the two waves of nearby frequencies are superimposed together. This will occurs when the two waves are travel in the same path. Beats also cause a periodic variation in the intensity of resultant waves.  The beat frequency is the no of beats formula produced per second. 

Beat Formula: fb =|f2−f1| 

f1 and f2 are the frequencies of the two waves. 

The value of beat frequency cannot be negative. 

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The above image shows the diagram of the beat frequency, constructive interference of beat frequency and destructive interference in beat frequency. 

Beat Frequency in Real Time 

Musicians will commonly use beats interference to check tuning at the perfect fifth, unison, or other simple harmonic intervals. Piano and organ tuners are also using this method to count beats, which are aiming to produce a particular number of specific intervals. 

Problems Based on Beat Frequency

Problem 1: Calculate the Beat Frequency if the Two Frequencies of Waves are 720Hz and 280 Hz Respectively?

Answer:

From the given data, lets consider the values of f1 and f2 as given below/ 

f2 = 700Hz and f1 = 300Hz

The formula for beat frequency 

fb = |f2−f1|

fb = |700−300|= 400Hz

Therefore, the beat frequency of the above given two waves is 400Hz. 

Problem 2: Derive the Beat Frequency of the Wave, with Frequencies are 650 Hz and 800 Hz Respectively?

Answer:

From the given data lets consider the values of f1 and f2 as given below. 

f1 = 650Hz and f2 = 800Hz

The beat frequency derivation (fb) 

 fb =|f2−f1|

fb= |800−650|= 150Hz

Therefore, the beat frequency of the above given two waves is 150Hz. 

The energy contained within the system is called internal energy. It is symbolized by the English letter ‘U.’ 

Internal energy is also called thermal energy. It is the energy of a substance due to kinetic and potential energies that are associated with the random motion of all the particles that make up the substance. 

In short, internal energy is the energy associated with the random motion or disordered arrangement of particles within the system, which is measured in KJ or Joule. We can calculate the same by the internal energy formula.

The change in internal energy equals the difference in the heat flow in a system and the work done by/on the system (PV) and the change in internal energy formula helps us calculate the same.

On this page, we will understand the internal energy formula, internal energy formula, ideal gas, specific internal energy formula, change in internal energy equation,  and the total internal energy formula.

Internal Energy Equation

As per the first law of thermodynamics, the energy of the universe is invariant. 

Also, the change in the internal energy of a system equals the total of the heat transferred and the work done. 

Besides this, the heat added/flown is equal to the sum of the change in the internal energy of the system and the PV work done.

The Internal Energy of Gas Formula is:

                   Q  =  ΔU  + W  ….(1)

                => ΔU  + PV

Rearranging the equation (1)  to get the formula for change in internal energy:

                  =>   ΔU  =  Q  –  PV …(2)

The equation (2) is also called the total internal  energy formula or the change in internal energy equation)

Total Internal Energy Formula

The total internal energy formula is the sum of transnational energies, rotational energies, binding energies, and chemical energies of all the particles in the system.

The internal energy also involves the potential energy. The potential energy remains stored in the form of chemical bonds, attraction, or repulsion.

Also, kinetic energy, which is because of the motion, translation, rotation, and vibration of particles within the system.

Change in Internal Energy Formula

The Change in Internal Energy Formula is:

                   ΔU  =  Q  +  W

Here,

U =  the total change in internal energy within the system

Q =  the heat exchanged between a system and its surroundings (outside the system)

W  =  work done by or on the system

Internal Energy Formula Ideal Gas

Despite the fact that in thermodynamics most frequently the change in internal energy ΔU is considered relevant for ideal gases unquestionably the absolute internal energy U can likewise be determined.

To do this, envision a gas enclosed in a chamber with a constant volume that is chilled off to absolute zero. In this expression, all the particles are stationary, and the gas, accordingly, has no internal energy. However, the heat Q is added at a constant volume to the gas until it arrives at a temperature of ‘T.’

All the heat that was necessary to heat the gas is ultimately present as internal energy U. Accordingly, at a temperature T the gas has the accompanying internal energy U is given as;                

Here, 

cv  =  the specific isochoric heat capacity, i.e., the specific heat capacity at constant volume

For ideal gases, cv can be temperature-dependent. 

Formula for Change in Internal Energy

The change of internal energy formula to derive the internal energy of gas formula is:

Taking equation (3) and writing it as per the formula of change in internal energy, we get:

                          

Here, equation (4) is the required specific internal energy formula.

Analogy Between Internal Energy and Gravitational Potential Energy

The internal energy of ideal gases can obviously measure up in similarity to the gravitational potential energy of an object While the gravitational potential energy addresses the energetic (gravitational) condition of an object at a given height ‘h,’ the internal energy addresses the energetic (kinetic) state of an ideal gas at a given temperature T. 

A given height h can be allocated specific potential energy by means of the mass m of the object. Similarly, specific internal energy can be allocated to a given temperature T by means of the mass m of the gas. 

The specific connection between the potential energy and the tallness ‘h’ is set up by the gravitational acceleration g (reliant upon the position!). On account of internal energy, the connection between internal energy U and temperature T is set up by the specific isochoric heat capacity cv (reliant upon the kind of gas!).

Conclusion

In the nutshell, the formula for change in internal energy relates to the heat flow and the work done by using the first law of thermodynamics.

Specific gravity is one of the properties of any fluid. The specific gravity is having much application even in our everyday life. In order to understand fluid dynamics, we must understand what is the specific gravity and the specific gravity formula as a priority. The specific gravity often is even referred to as the relative density and it is a dimensionless entity. The density of the object majorly determines this factor. In this topic, we will discuss what is specific gravity, what is specific gravity formula and a small derivation of specific gravity formula along with solved examples.

Specific Gravity of Liquid

The specific gravity of liquid refers to the ratio of the density of an object or the fluid and the reference material, usually, water is considered as reference material for fluids and air for gases. Furthermore, the specific gravity of a liquid or an object can tell us if the object will sink or float in reference material. Besides, the reference material for liquids is water that always has a density of either 1 gram per cubic centimetre or 1000 kg/m³ and the specific gravity of water is always one.

In general, we can say the specific gravity defines whether an object will sink or float in water. Anyways, there are many other factors that determine whether an object will float or sink, such as density, specific weight, etc. The specific gravity of the object is always denoted by the letter S.

Application of Specific Gravity

The main application of specific gravity is that it lets us decide whether the given object is denser than the water or not. If the specific gravity of the object is less than the specific gravity of water i.e., S ＜ 1 then the object will float on the water. At the same time if the specific gravity of the object is found to be greater than the specific gravity of water i.e., S > 1 then the object will sink in the water. For example, we can think of a plastic ball floating on water. 

If we know the specific gravity of any material then we can easily determine the density of the material. Let us have a look at the specific gravities of a few familiar objects:

• The specific gravity of water = 1

• The specific gravity of mercury = 13 . 6

• The specific gravity of aluminium = 2.72

• Specific gravity of gold = 19.3

What Is Specific Gravity Formula?

Let us have a look at the specific gravity of liquid derivation to understand what is specific gravity formula. According to the definition of specific gravity, we can formulate the same mathematically as follows:

⇒ S = [frac{rho_{object}}{rho_{water}}]

Where,

[rho][_{object}] – The density of the object or the material under consideration

[rho][_{water}] – The density of the water (or the reference material depending upon the material used)

Since both the numerator and the denominator have the same units (i.e., both are densities), hence they cancel out each other, thus the specific gravity is a dimensionless physical quantity. From the specific gravity formula, it is clear that the specific gravity is directly proportional to the density of the materials. In order to calculate the specific gravity, we must first know how to calculate the density of the materials.

The density of the materials can be calculated by using the formula:

⇒ [rho] = [frac{mass}{volume}] = [frac{m}{v}] Kg/m[^{3}]

We know that the mass of an object can be in grams, kilograms, and pounds, irrespective of the unit of measurement the density of the object can be determined. At the same time, the density directly relates to the mass of the object. So, we can also rewrite the specific gravity by dividing the mass of an object with the mass of the water without violating the laws of physics. Thus, the specific gravity formula in terms of mass is given by:

⇒ S = [frac{text{mass of the object}}{text{mass of the water}}] 

And from the theories of physics, we have seen that the mass of the object is also directly related to density. Also, from Newton’s law, we know that the mass is measured in Newtons. Hence, we can also calculate the specific gravity of an object with the help of the weight of the object and water, and it is given by the formula:

⇒ S = [frac{text{Weight of the object}}{text{Weight of the water}}] 

One of the important points to note down here is that in all these formulas of specific gravity all the units are the same and they cancel each other out.

Solved Examples:

1. A liquid has a mass of 45 grams and the volume of the water (reference material) is 5 ml. Then calculate the specific gravity of the object? Also, specify whether the object will sink or float in the water? 

(Note: Consider the density of the water is 1 gm/ml) 

Sol:

Given,

The mass of the object = m = 45 grams

The volume of the water = V = 5 ml

The density of water = [rho][_{water}] = 1gm/ml

We are asked to determine the specific gravity of the given object. Before we start calculating the specific gravity, we must determine the density of the given object.

Thus, the density of the given object is given by:

⇒ [rho][_{object}] = [frac{mass}{volume}] = [frac{45}{5}] = 9 gm/ml…..(1)

Therefore, the specific gravity formula is given by:

⇒ S = [frac{rho_{object}}{rho_{water}}] …..(2)

Where,

[rho][_{object}] – The density of the object or the material under consideration

[rho][_{water}] – The density of the water 

Substituting all the values in equation (2) and simplify. We get:

⇒ S = [frac{9}{1}] = 9

Thus, the specific gravity of a given object is 9. Since the specific gravity of the object is more than 1 i.e., S > 1, the object will sink in the water.

2. A liquid has a mass of 10 grams and the volume of the water (reference material) is 12 ml. Then calculate the specific gravity of the object? Also, specify whether the object will sink or float in the water? 

(Note: Consider the density of the water is 1 gm/ml) 

Sol:

Given,

The mass of the object = m = 10 grams

The volume of the water = V = 12 ml

The density of water = [rho][_{water}] = 1gm/ml 

We are asked to determine the specific gravity of the given object. Before we start calculating the specific gravity, we must determine the density of the given object.

Thus, the density of the given object is given by:

⇒ [rho][_{object}] = [frac{mass}{volume}] = [frac{10}{12}] = 0.8 gm/ml …..(1)

Therefore, the specific gravity formula is given by:

⇒ S = [frac{rho_{object}}{rho_{water}}] …..(2)

Where,

[rho][_{object}] – The density of the object or the material under consideration

[rho][_{water}]  – The density of the water 

Substituting all the values in equation (2) and simplify. We get:

⇒ S = [frac{0.8}{1}] 

Thus, the specific gravity of given objec
t is 0.8. Since the specific gravity of the object is less than 1 i.e., S < 1, the object will float in the water.

The force of attraction is a force that draws the body close to it due to an attraction. In nature, several attraction forces exist. These are the electric force, magnetic force, electrostatic force, gravitational force, and electromagnetic force. Gravitational force is a well-recognized force that attracts the body towards it despite the distance. Through Newton’s Gravitational force we get a lot of clarification regarding this force and how it operates. It states that the mass existing in the Universe attracts some or other mass prevalent in the universe. It validates that anything that is thrown up eventually comes down. The formula of the force of attraction is based on this theory. 

Representation of Force of Attraction Equation

Suppose there are two masses denoted by ma and mb separated by a space. Then the force of attraction formula is stated by 

 

F_g = [frac {(G m_a m_b)} {d^2}]

 

Where, 

 

F= force of attraction

 

G= gravitational constant

 

m_a= mass of the first object a

 

m_b= mass of second object b

 

d = distance between two objects d

 

This force of attraction formula helps in the calculation of any two bodies having a greater mass as the smaller mass is insignificant. 

 

Even when things are not in close proximity, the force of attraction draws them together. Learn about the three forces of gravitational, electrical, and magnetic attraction, as well as their formulae and concepts.

What is meant by Gravity?

Gravity is probably the most well-known force of all. We people on Earth imagine gravity as an apple landing on Isaac Newton’s head. It is only due to the gravity that we observe things falling to the ground. Similar instances occur throughout the universe as well. However, this is merely our perception of gravity. In reality, just as the earth pulls the apple towards it owing to gravity, the apple also pulls the earth. The problem is that the earth is so enormous that the gravitational interactions of every other item on the globe are overwhelmed. 

Every item with mass has a gravitational pull on everything else. This force explains why the planets orbit, among other reasons. Furthermore, everything, including you, pulls every other object in the cosmos, which is known as Newton’s Universal Law of Gravitation. The acceleration of the moon as compared to the acceleration of things on Earth by Issac Newton. Newton was able to derive an important conclusion regarding the dependency of gravity on distance by believing that gravitational forces were responsible for each. He came to the conclusion that the gravitational pull between the Earth and other things is inversely proportional to the distance between the Earth’s center and the object’s center based on this comparison. However, distance isn’t the only factor that influences the amplitude of gravitational forces.

What Do You Mean by Electric Force?

The electric force, also known as the electrostatic force, is the second force that may induce attraction. While gravity affects mass things, electrostatic forces impact charge objects. The quantity of electrons and protons in a thing determines its charge. Most items are electrically neutral, which means they contain an equal number of electrons (which have a negative charge) and protons (which have a positive charge). Objects can, however, lose electrons and become positively charged, or absorb electrons and become negatively charged. As a result, positive and negative charges will attract one another. As a result, the adage “opposites attract” is true.

What is Magnetic Force?

The magnetic force is the third force that may produce attraction. Objects with magnetic characteristics are attracted by the magnetic force. A magnet attracts iron-rich metals, such as steel, as well as nickel and cobalt. When a north magnetic pole is placed close to a south magnetic pole when an object is magnetized, the magnetic force is attracted. Electric currents are the primary source of magnetism. There is an electric current when charges move. The electric force affects charges that do not move, while the magnetic force affects charges that move. The proverb ‘Opposites attract’ may also be explained by magnetic attraction.

Factors affecting the Three Forces of Gravitational, Electrical, and Magnetic Attraction

The gravitational force is equal to the product of the masses, m1 and m2, and inversely proportional to the square of the distance between the two masses, denoted by r. The attraction is inversely proportional, which implies that it is strong when the masses are near to each other and weak when they are far apart.

The force of electrical attraction is proportional to the product of the charges, and it is inversely proportional to the square of the distance between the charges, exactly like gravitation. There exists an attraction between a positive and a negative charge separated by r.

The force is stronger when the charges are near to one another, and weaker when the charges are further apart, just as the gravitational force.

Metal atoms contribute electrons to nonmetal atoms when metals and nonmetals combine to create compounds. Because of the loss of negatively charged electrons, metal atoms become positive ions, whereas nonmetal atoms become negative ions. Ions display attraction forces toward ions with opposite charge, giving rise to the saying “opposites attract.” Coulomb’s law governs the force of attraction between oppositely charged ions: F = k * q1 * q2 / d2, where F is the force of attraction in Newtons, q1 and q2 are the charges of the two ions in coulombs, d is the distance between the nuclei of the two ions in meters, and k is a proportionality constant of 8.99 x 109 Newton square meters per square coulomb.

Conclusion 

The formula of force of attraction is important to understand the concept of gravity that works on the earth. Moreover, when we calculate force of attraction it also explains the gravitational phenomenon that happens in space. 

The maths final quantity which is discussed in Lesson 1 is acceleration. The definition of acceleration can be stated as:

Acceleration can be defined as a vector quantity that defines the rate at which an object changes its velocity. An object is still accelerating if it is changing its velocity time and again.

Occasionally Sports announcers say that a person is accelerating if they are moving fast. Still, acceleration has nothing to do with going fast or slow that is with the speed. A person can be moving very fast or slow and still not be accelerating. Acceleration has to do nothing with changing how fast an object is moving. If an object does not change its velocity then the object is not accelerating. The data which is at the right are representative of a northward-moving object does accelerate. The velocity of the object is changing over the course of time. In fact the velocity is changing by a constant amount – that is 10 m/s – in each second. Anytime an object’s velocity is changing the object is said to be in an accelerating motion or it has an acceleration.

Constant Acceleration 

At times an accelerating object will change its velocity by the same amount each time or second. This is then referred to as acceleration which is constant since the velocity is changing by a constant amount each second. With a constant acceleration an object should not be confused with an object with a constant velocity. Don’t be fooled by these two confusing terms! If an object is changing its velocity no matter whether by a constant amount or even a varying amount  then it is an object which is accelerating. An object with a constant velocity is not said to be accelerating. We should ponder and note that each object has a changing velocity.

Since objects accelerating are constantly changing their velocity one can say that the distance traveled upon a time is not a constant value. If we keenly observe the motion of a free-falling object that is free fall, we would observe that the averages a velocity of object of approximately 5 m/s in the first second, which is approximately 15 m/s in the second second, which can be said to be approximately 25 m/s in the third second. Our object which is free-falling would be constantly accelerating. Given these velocity which is average values during each consecutive 1-second time interval we can easily say that the object would fall 5 meters in the first second then 15 meters in the second second for a total distance of 20 meters then later 25 meters in the third second for a total distance of 45 meters and 35 meters in the few seconds later for a total distance of 80 meters. 

Acceleration Vector Direction 

Since we already know that the acceleration is a vector quantity, it has a direction associated with it as well. 

whether the object is moving in the direction which is negative or positive.

The general principle for determining the acceleration are mentioned below:

If an object is slowing down then the acceleration in it is in the opposite direction of its motion.

This general principle is usually applied to determine whether the sign of the acceleration of an object is negative or positive, left or right, down and up etc. if we observe multiple different cases then in each case, the acceleration of the object is in the direction which is positive. 

In Example  the object is moving in the direction which is positive direction, that is it has a positive velocity and is speeding up. Thus this object has an acceleration which is positive acceleration. If we see other examples  the object is moving in the negative direction and it has a negative velocity and is slowing down. According to our general principle we can conclude that when an object is slowing down then the acceleration is in the opposite direction as the velocity. Thus the object also has an acceleration which is positive.

Motion which is Circular 

In case of uniform circular motion, that is moving with a speed which is constant speed along a circular path, a particle then experiences an acceleration which is resulting from the change of the direction of the velocity vector, while the magnitude remains same or constant. The derivative of the object of location of a point on a curve with respect to time that is  its velocity, turns out to be exactly tangential to the curve always. We have seen that in uniform motion the velocity in the tangential direction does not change at all and the direction of acceleration must be in radial direction, which is pointing to the center of the circle.

Aerofoil is also called an airfoil. It is a surface shaped like an airplane wing, tail, or propeller blade, that produces lift and drag when moved through the air. An aerofoil generates a lifting force that acts at right angles to the airstream and a dragging force that acts in the same direction as the airstream. High-speed aircraft mainly implement low-drag, low-lift airfoils that are thin and streamlined and on the other hand, slow aircraft that carry heavy loads use thicker airfoils with high drag and high lift. 

What is Aerofil?

Aerofoil refers to a cross-sectional shape having a design with a curved surface that provides the most favourable ratio between lift and drag in flight. Lift is the component that helps the force turn out to be perpendicular to the motion’s direction while drag is the component that is parallel to the motion’s direction.

Aerofoil or also known as Airfoil is a structure with curved surfaces designed to give the most favourable ratio of lift to drag in flight, which is mainly used as the basic form of the fins, wings, and tailplanes of most aircraft. Aerofoil is the cross-section design of the wing, blade, or sail. Lift is the component such that the force is perpendicular to the direction of motion and drag is the component parallel to the direction of motion. A similar idea is being used in the designing of hydrofoils which is used when water is used as the working fluid. A body that is airfoil-shaped, moving through a fluid produces an aerodynamic force. The design of the aerofoil depends on the weight, speed, and purpose of the aircraft and mainly depends on the aerodynamic characteristics. These are dependent on certain terms that need to be defined to understand the design.

Aerofoil Terminology

An aerofoil consists of various cross-sectional shapes. Different types of aerofoils are used for the construction of aircraft wings. To differentiate between different aerofoil shapes, an aerofoil’s properties are defined and specific terminologies are used. Aerofoil Terminology. An Aerofoil is being designed with a shape that has the capability of producing lift with relatively high efficiency as it passes through the air. An aerofoil can have many cross-sectional shapes. The terms which are related to aerofoils are as follows.

• Chord: Chord can be defined as the distance between the leading edge, at the front of the aerofoil that is the point, and has maximum curvature and the trailing edge, at the rear of the aerofoil, that is the point with a maximum curvature along the chord line. It is a distance between the leading and trailing edges measured along the chord line.

• Chord Line: Chord line is the straight line connecting the leading and trailing edges.

• Leading-Edge: It is an edged part of an aerofoil that hits the air particles first.

• Lower Surface: The lower surface is a higher static pressure surface which is also known as a pressure surface. It is the surface of an aerofoil between the leading and trailing edges, on the lower side.

• Mean Camber Line: It is a line joining the leading and trailing edges of an aerofoil, at an equal distance from the upper and lower surfaces.

• Maximum Camber: It is the maximum distance of the mean camber line from the chord line.

• Maximum Thickness: It is the maximum distance of the lower surface from the upper surface.

• Trailing Edge: It is an edged part from an aerofoil that hits the air particles last.

• Upper Surface: The upper surface is associated with high velocity and low static pressure, which is also known as suction surface. It is the surface of an aerofoil between the leading and trailing edges, on the upper side.

(Image to be added soon)

When the aerofoil is moving through a fluid, the following are the terms used to describe the behaviour:

1. Aerodynamic Center: The centre where the pitching moment is independent of lift coefficient and angle of attack.

2. Center Of Pressure: The centre where the pitching moment is zero.

3. The Angle Of Attack (AOA): The angle of attack is formed between a reference line on a body and the oncoming flow.

4. Pitching Moment: The moment or torque produced on the aerofoil by the aerodynamic force is known as the Pitching moment.

Lift Coefficient

The lift coefficient is a relationship between the lift generated by a lifting body to fluid density, fluid velocity, and the associated reference area, this is a dimensionless coefficient. Mathematical representation is as follows:

C[_{L}] = [frac{L}{q_{s}}] = [frac{L}{frac{1}{2}p.u.u.s}] = [frac{2L}{p.u.u.s}]

Where,

C[_{L}] : lift coefficient

L: lift force

S: relevant surface

q: fluid dynamic pressure

ρ: fluid density

μ : flow speed

Types of Aerofoil 

The types of aerofoils that are used are as follows:

1. Symmetrical Aerofoil:

This has identical upper and lower surfaces that produce no life at zero AOA such that the chord line and mean camber line are the same. In most of the light helicopters in their main rotor blades, these applications are fine. It is the type of aerofoil that has identical upper and lower surfaces such that the chord line and mean camber line happen to be the same, resulting in the production of no life at zero angles of attack. Symmetrical aerofoil has application in the main rotor blades of various light helicopters.

2. Non-symmetrical Aerofoil:

Non-symmetrical aerofoil has different upper and lower surfaces such that the chord line is placed above with large curvature, and it is also known as a cambered aerofoil. This aerofoil is also known as cambered aerofoil and it has different upper and lower surfaces such that the chord line happens to be placed above with large curvature. The chord line and chamber line of Non-symmetrical aerofoil are different and the advantages of this type are a better lift to drag ratio and stall characteristics, thereby resulting in the production of a useful lift at zero angles of attack.

3. These have different chord lines and chamber lines. These are the advantages of a non-symmetrical aerofoil, tha
   t is the lift to drag ratio and stall characteristics are better and useful lift is produced at zero AOA. The only disadvantages are that they are not economical and there is a production of undesirable torque.

(Image to be added soon)

Fun Facts

1. In American English it is Airfoil and in British English, it is known as Aerofoil.

2. An Aerofoil or Airfoil is the shape of a wing or blade of a propeller.

3. Aerofoil was invented by Sir George Cayley.

4. Aerofoil will provide either lift or downforce, when it is moving through a fluid, depending on what it is used for.

5. According to Newton’s third law, the air must exert equal and opposite force on the airfoil, which is known as lift.

6. Birds fly on the basis of airfoils for wing-lift.

7. The underwater fins of sailboats, such as centerboards, are also lifting foils and operate on the same principles as airfoils. Technically they should be called hydrofoils, but this term has already been taken; generally, they are just referred to as “foils”

It is important to note that any thin object such as a flat plate or even the deck of a bridge, at an angle of attack with respect to the airflow, will generate lift; there is nothing “magic” about the shape of an airfoil. However, the lift is generated with the minimum of drag, so it is important for efficiency, the airfoil shape ensures that.