Phsyics Of The Atmosphere Flashcards
What is the SI unit of mass?
Kilograms
What is the SI unit of density?
Kg/m^3
Give 4 fundamental units used in aerodynamics
Length (meters)
Mass (kilogram)
Time (seconds)
Temperature (Kelvin)
What is the unit of speed?
m/s
What is the symbol used for speed?
v
What is the change in speed over time known as?
Acceleration
What is the symbol used for acceleration due to gravity?
g
What is the SI unit of Acceleration?
m/s^2
What is the formula for weight?
Weight = mass x gravity
What is the unit of force?
Newtons
What is the formula for Power?
Power = work done / time
What is the unit for Work?
Joules
What is the SI unit of pressure?
N/m^2
What is the symbol used for static pressure?
p
What is the formula for Pressure?
Pressure = Force / Area
What is static pressure?
Pressure that acts in all directions
What is dynamic pressure?
Pressure that acts in the direction of flow
What is the symbol for dynamic pressure?
q
What is the symbol for the speed of sound?
a
Give the formula for the speed of sound and give the constant and variable
20 x sq.rt of T
20 - constant
T - variable
What is the unit of temperature in the speed of sound?
Kelvin
Why is the speed of sound less at high altitudes?
Lower temperature as air molecules have less energy for transfer
Where is the position of the pressure waves if an aircraft is flying below the speed of sound?
Pressure waves move ahead and behind the aircraft
What is the region called where the aircraft moves below the speed of sound?
Subsonic
What is the region where the aircraft moves at the speed of sound?
Transonic
Where is the position of the pressure wave if the aircraft is flying at the same speed as the speed of sound?
Pressure waves form closely at the front of the aircraft as it cannot escape. Pressure waves are known as shock waves
What is the region where the aircraft is flying at a speed above the speed of sound?
Supersonic
Where is the position of the pressure wave if the aircraft is flying at a speed above the speed of sound?
Pressure waves increase behind the aircraft and shock waves form outside the periphery
What is Mach Number?
The relationship between the aircraft speed and the speed of sound
What is the formula for Mach number?
Speed of aircraft / speed of sound
What symbol is used for the Mach Number?
M
What does a Mach Number = 1 mean?
The aircraft is flying at the speed of sound
What is the critical mach and in which region is it found?
The maximum speed the aircraft can fly at without firming shock waves
Found in the subsonic region just before it hits the transonic
In which region does a Mach number of more than 1 but less than 1.3 sit?
Transonic
What region would a mach number higher than 1.3 be in?
Supersonic
Define atmosphere
The mass of the air extending upwards from the surface if the earth
What is the lowest layer of the atmosphere known as?
Troposphere
What is the boundary between the troposphere and the stratosphere?
Tropopause
In which part of the atmosphere does temperature, pressure and density vary in?
Troposphere
What is the standard altitude for the tropopause?
11km
What is the standard temperature at the tropopause?
-56.5 degrees C
By how much does the temperature decrease with altitude under standard conditions?
6.5 degrees/km
What is the height of the tropopause over the north pole?
8km
What is the height of the tropopause over the south pole?
8km
What is the height of the tropopause over the equator?
16km
What is ICAO?
International Civil Aviation Organisation
By how much does the temperature increase or decrease in the stratosphere?
It is constant
What is the temperature, pressure and density at standard sea level?
Temperature - 288K
Density - 1.225 kg/m^3
Pressure - 1013.25 Pa
What does ISA stand for?
International Standard Atomosphere
