8.1 Physics Of The Atmosphere Flashcards
What is the unit of mass?
Kg
What is the SI system?
It is based on the metric system and must be used as law throughout the world
What is the definition of 1kg of mass?
The volume of one litre of pure water at 4°C
What is the unit of length?
Metre (m)
What is the unit of time?
Second (s)
What is the unit of temperature?
Kelvin (K)
What is the acceleration due to gravity?
9.8 m/s^2
What are the 4 fundamental units of aerodynamics?
Mass, temperature, length and time
What is weight measured in?
Newton’s (N)
What is work?
Force multiplied by the distance (measured in Joules (J))
What is power measured in?
Watts (same as Newton metres per second)
What is the symbol for static pressure?
A small “p”
What is the symbol for dynamic pressure?
Small letter “q”
What is static pressure?
The pressure acts in all directions
- measured in N/m^2
What is dynamic pressure?
Pressure that acts only in one direction
- measured in Bar
What is 1 bar equal to?
100,000 pascal (Pa)
- deca-Newtons per square centimetre
What is the speed of sound denoted by?
Small letter “a”
Measured in m/s
What would a Mach number of 1 denote?
The aircraft is travelling at the speed of sound
How is the Mach number calculated?
speed of the aircraft
—————————
speed of sound
What is the pressure wave created as an aircraft travels at the speed of sound called?
The shock wave
What are the three sound regions?
- subsonic
- transonic
- supersonic
What is the critical Mach number?
The maximum speed before the formation of shock waves
What are the two distances above the earth of the tropopause?
Equator = 16 kilometres Poles = 8 kilometres
What are the three parts of the atmosphere?
- Stratosphere
- Tropopause
- Troposphere
Who introduced the standard atmosphere?
The ICAO
What is the standard for the tropopause according to the ISA?
11 kilometres
What does ISA stand for?
International Standard Atmosphere
Under standard conditions, what does the temperature decrease by with altitude?
6.5 degrees per kilometre
What is the standard temperature of the tropopause?
- 56.5 degrees Celsius
Where in the atmosphere is there no temperature change?
The stratosphere
Which level of the atmosphere contains the weather conditions such as clouds and rain?
The troposphere
What is the equation for speed?
Speed = distance
————
time
What is the equation for acceleration?
Acceleration = change in velocity
————————
time taken
What happens to the weight of an object if it is subject to a constant velocity?
There is no change to the weight
What happens to the weight of an object if it is subject to acceleration?
The weight of the object increases due to the added force
What is the formula for dynamic pressure?
Pressure = 1/2 P V^2
What is the formula for static pressure?
P = Pgh
What is the temperature, pressure and density at standard sea level?
Temp: 288K
Pressure: 1013 hecto-Pa
Density: 1.225 kg/m^3
