Aerodynamics and SI Units Overview

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Questions and Answers

What is the unit of measurement for length in the International System (SI) of units?

Nautical Miles (nm)

Metres (m) (correct)

Kilograms (kg)

Seconds (s)

What is the unit of measurement for velocity?

Metres per second (m/s) (correct)

Newton (N)

Kilograms (kg)

Metres (m)

What is the formula for calculating force?

Force = Mass x Velocity

Force = Mass x Acceleration (correct)

Force = Momentum x Acceleration

Force = Weight x Acceleration

Which of the following is NOT a fundamental SI unit?

Area Signup and view all the answers

What is the unit of measurement for weight?

Kilograms (kg) Signup and view all the answers

What does the term 'knot' refer to in aeronautics?

The unit of measurement for airspeed Signup and view all the answers

What is the unit of measurement for force?

Newton (N) Signup and view all the answers

What is the definition of momentum?

The product of the mass and the velocity of a body Signup and view all the answers

Which of these is a form of energy due to motion?

Kinetic Energy Signup and view all the answers

What is the relationship between work and power?

Power is the rate at which work is done Signup and view all the answers

What is the unit of measurement for pressure?

Pascal Signup and view all the answers

What is the relationship between mass and weight?

Weight is the force of gravity acting on a body Signup and view all the answers

What is dynamic pressure in aviation?

Pressure created by moving air brought to rest on a surface Signup and view all the answers

What does dynamic pressure (q) depend on?

Air density and altitude Signup and view all the answers

What is total pressure (PT)?

Sum of static and dynamic pressures Signup and view all the answers

Which of the following affects air density?

Changes in pressure, temperature, and humidity Signup and view all the answers

How is temperature measured in scientific calculations?

In Kelvin (K) only Signup and view all the answers

What describes viscosity in aerodynamics?

The resistance to movement of air layers Signup and view all the answers

What is wing loading defined as?

Total aircraft weight supported per unit area of the wing Signup and view all the answers

Indicated Airspeed (IAS) is crucial for providing information about which aspect?

Stalling and structural limitation airspeeds Signup and view all the answers

How is one Celsius degree converted to Kelvin?

By adding 273 Signup and view all the answers

Which airspeed measurement is corrected for compressibility error at a particular altitude?

Equivalent Airspeed (EAS) Signup and view all the answers

Which airspeed measurement is equal to the True Airspeed in standard atmosphere at sea level only?

Calibrated Airspeed (CAS) Signup and view all the answers

Which of the following is not a factor used to calculate True Airspeed?

Indicated Airspeed Signup and view all the answers

What is the relationship between True Airspeed (TAS) and Equivalent Airspeed (EAS)?

TAS = EAS (ρo / ρ)1/2 Signup and view all the answers

What is the definition of Mach Number?

The ratio of the TAS of an aircraft to the speed of sound in the surrounding atmosphere. Signup and view all the answers

Newton's first law of motion states that a body will continue in a state of rest or in uniform motion in a straight line unless acted upon by an external force. This tendency of a body to resist changes in motion is called?

Inertia Signup and view all the answers

What does Newton's third law of motion state?

For every action there is an equal and opposite reaction. Signup and view all the answers

Study Notes

Introduction

Aerodynamics requires a strong foundation in basic mechanics and units of measurement
Worldwide measurements are based on the International System (SI) of units, though some variations exist (e.g., altitude in feet, airspeed in knots)

SI Units

Fundamental SI units include mass (kilograms), length (meters), and time (seconds)
Derived units are commonly used in aerodynamics

Derived Units

Area: A measure of a surface (square meters)
Volume: A measure of space occupied by a body (cubic meters)
Velocity: A measure of motion in a specific direction (meters per second)
Acceleration: The rate of change of velocity (meters per second squared)
Momentum: The product of mass and velocity (kilogram meters per second)
Force: External influence changing rest or motion; proportional to rate of change of momentum (Newton)

Weight

Gravitational force of attraction exerted by the Earth on an object (kilograms)
Weight = Mass × Acceleration due to Gravity
Weight varies based on location and altitude; standard value is 9.81 m/s²

Work

Effort to move an object a set distance in the direction of the force
Unit of work is the Joule (J), equivalent to 1 Newton-meter (Nm)
Work = Force × Distance

Power

Rate of doing work (Watts)
Power = Force × Velocity
1 Watt = 1 Joule/second (J/s) or 1 Newton-meter/second (Nm/s)

Energy

Capacity to do work; exists in potential and kinetic forms
Potential Energy: Energy due to position
Kinetic Energy: Energy due to motion
Unit of energy is the Joule

Pressure

Force per unit area (Pascals or N/m²)
Common unit in aviation is the bar (1 bar = 10⁵ Pa) or millibar
Types of pressure: static pressure and dynamic pressure

Static Pressure

Stationary air exerts pressure equally in all directions
Example: Air in a container exerts pressure on the walls

Dynamic Pressure

Occurs when moving air is brought to rest on a body's surface (relative movement between surface and airflow)
Dynamic Pressure = 0.5 * Density * Velocity²
Density (ρ) decreases with altitude; Velocity (V) is the speed relative to the airflow

Total Pressure

Sum of static and dynamic pressures
Important for aerodynamic calculations (lift, drag, and indicated airspeeds)

Density

Mass of material per unit volume (kilograms per cubic meter)
Important property in aerodynamics; varies with pressure, temperature, and humidity

Temperature

Measure of hotness
Units: Degrees Celsius (°C) or Kelvin (K)
Converting between Celsius and Kelvin: K = °C + 273

Viscosity

Resistance to motion of fluid layers
Example: Viscosity of engine oil varies based on temperature

Wing Loading

Total aircraft weight supported per unit wing area (Newtons per square meter)
Wing Loading = Aircraft Weight / Wing Area

Airspeeds

Indicated Airspeed (IAS): Airspeed shown on the pitot-static airspeed indicator, uncorrected for instrument or atmospheric errors
Calibrated Airspeed (CAS): IAS corrected for instrument and position errors
Equivalent Airspeed (EAS): CAS corrected for compressibility errors
True Airspeed (TAS): Actual speed of aircraft relative to the air; unaffected by aircraft
Mach Number: Ratio of TAS to the speed of sound in the surrounding air

Newton's Laws of Motion

First Law: Body in rest or uniform motion stays in that state unless acted on by an external force
Second Law: Acceleration of a body is directly proportional to the force acting on it
Third Law: For every action, there is an equal and opposite reaction

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Description

This quiz explores the fundamental concepts of aerodynamics with a focus on the International System of Units (SI). It covers basic mechanics as well as derived units such as area, volume, velocity, and force, key to understanding aerodynamic principles. Test your knowledge on these essential metrics and their applications in aerodynamics.