Properties of air

Question 1

What percentage of the atmosphere is composed of Carbon Dioxide?

Answer 1

Less than 1%

Question 2

Density is maximum or minimum at sea level

Answer 2

Maximum

Question 3

Aircraft performance is best in an atmosphere of high density or Low density.

Answer 3

Aircraft performance is best in an atmosphere of high density.

Question 4

Define the term Pressure

Answer 4

The total force acting on a given surface area.

Question 5

Define the term Temperature

Answer 5

The kinetic energy of the substance. (How fast they vibrate)

Question 6

What atmospheric conditions will result in best aircraft performance

Answer 6

Low Temperature, High Pressure

Question 7

ISA

Answer 7

International Standard Atmosphere

Question 8

What is the pressure lapse rate until 5000 ft?

Answer 8

1 hPa per 30ft

Question 9

statements regarding ISA conditions. With an increase in altitude……

Answer 9

Temperature slowly decreases steadily by 1.98 degrees per thousand feet,

Temperature decreases until the tropopause,

Temperature stops decreasing once it reaches -56.4 degrees.,

Density decreases (Quickly at first),

Pressure decreases by 30 ft per hPa (then slower past 5000ft)

Question 10

What is the ISA temperature lapse rate until the tropopause?

Answer 10

The ISA temperature at sea level is 15°C. It decreases with altitude at a rate of 1.98 degrees every 1000 ft until the temperature is -56.4 degrees

Question 11

What is the ISA Pressure at sea level?

Answer 11

The ISA pressure at sea level is 1013.2hPa. It decreases with altitude at a rate of 1hPa every 30 ft until 5000 ft, and then at a lower rate higher up.

Question 12

Aircraft performance is highest when density altitude is high(True/False)

Answer 12

False

Question 13

Pressure altitude Formula

Answer 13

Aircraft elevation + (30 x (1013-QNH)

Question 14

Density altitude Formula

Answer 14

Density altitude = Pressure Altitude + (120 x (Actual temperature - ISA temperature at pressure altitude))

Question 15

Two locations at sea level have the same temperature and pressure, but one location is very dry and one is very humid. Aircraft performance will be BEST at which location.

Answer 15

The humid atmosphere has water particles that replace the dry air particles. These water particles have less mass, meaning the air will be less dense.

An atmosphere with a reduced density will result in lower aircraft performance.

The correct answer is: Very dry location

Question 16

What percentage of the atmosphere is composed of Oxygen?

Answer 16

21%

Question 17

Assuming that the temerature of the gas remains constant in these situations,

Answer 17

The greater the density of the air, the greater the number of molecules there are colliding with the surface. This creates a greater force on a given area, meaning higher pressure.

The correct answers are: Increased density means an increased pressure, Increased volume means an decreased pressure

Question 18

Density can be measured directly and is indicated in the cockpit.

Answer 18

As a property, it’s very difficult, if not impossible to measure density directly, due to the difficulty in measuring the mass of a gas, imagine trying to count the number of molecules of air floating around in an empty glass.

The correct answer is ‘False’.

Question 19

Select the correct statement.

a. Pressure remains constant regardless of altitude because density and temperature cancel each other out
b. Pressure reduces with altitude. Slowly initially, and then at a larger rate higher up
c. Pressure reduces with altitude. Quickly initially, and then at a lower rate higher up
d. Pressure reduces at a constant rate with altitude

Answer 19

Pressure reduces with altitude. Quickly initially, and then at a lower rate higher up

Question 20

In a flexible container that can expand or contract, is a gas substance. Select the correct statement(s) for the gas that is heated.

Answer 20

Density reduces, Pressure will remain equal to the surrounding air

Question 21

What atmospheric conditions will result in poorest aircraft performance

Answer 21

High Temperature, Low Pressure

Question 22

When the pilot selects 1013 hPa on their altimeter subscale, the altimeter reading will indicate…..

Answer 22

Pressure altitude

Question 23

What is the ISA density at sea level?

Answer 23

The ISA density at sea level is 1.225kg/m³. It decreases with altitude rapidly at first then at a lower rate higher up.

Question 24

What is the ISA temperature at sea level?

Answer 24

15°C.

Question 25

If the pressure altitude was 10,000 ft and the corrosponding temperature was 9°C, what is the temperature deviation from ISA?

Answer 25

In ISA conditions, the sea level temperature is 15°C. This temperature reduces at a lapse rate of 2° per 1000 ft. So at 10, 000 ft the temperature has dropped 20°. (15°C - 20°C = -5°C) The ISA temperature at 10,000 ft is -5°C.

The actual temperature is 9°C which is 14° hotter than ISA. The ISA deviation is Δ 14°C.

The correct answer is: Δ 14°C

Question 26

What is the purpose of ISA?

Answer 26

a. To compare aircraft performance
b. For performance calculations
c. To judge performance on the day

Question 27

Aircraft performance is highest when density altitude is high(True/False)

Answer 27

A low density altitude indicates a high atmospheric density. This results in higher aircraft performance.

The correct answer is ‘False’

Question 28

What percentage of the atmosphere is composed of Nitrogen?

Answer 28

78%

Question 29

For conventional flight, density is required to become airborne.

Select one:
True
False

Answer 29

The correct answer is ‘True’.

Question 30

As an aircraft _______ the performance will reduce.

Answer 30

Climb

Question 31

Aircraft performance is greatest when taking off from aerodromes at a _____ altitude.

Answer 31

Low

Question 32

In New Zealand Aviation, atmospheric pressure is measured in……

Answer 32

HectoPascals (hPa)

Question 33

In a sealed container that cannot expand or contract, is a gas substance.
Select the correct statement(s) for the gas that is heated.

Answer 33

Density remains the same,

Pressure increases

Question 34

What is the pressure lapse rate until 5000 ft?

Answer 34

1 hPa per 30ft

Question 35

When the pilot selects 1013 hPa on their altimeter subscale, the altimeter reading will indicate…..

Answer 35

Pressure altitude

Question 36

a. Density reduces at a constant rate with altitude
b. Density remains constant regardless of altitude because pressure and temeperature cancel each other out
c. Density reduces with altitude. Quickly initially, and then at a lower rate higher up
d. Density reduces with altitude. Slowly initially, and then at a larger rate higher up

Answer 36

The correct answer is: Density reduces with altitude. Quickly initially, and then at a lower rate higher up

Question 37

Density can be measured directly and is indicated in the cockpit.(True/False)

Answer 37

‘False

Question 38

Select the correct statement regarding aircraft performance.

Select one:

a. Aircraft performance is best in an atmosphere of minimal density
b. Aircraft performance is not affected by atmospheric density.
c. High density means aircraft can take off and land from longer runways
d. Aircraft performance is best in an atmosphere of high density

Answer 38

The correct answer is: Aircraft performance is best in an atmosphere of high density

Question 39

Aircraft performance is greatest when taking off from aerodromes at a _____ altitude.

Answer 39

Low

Question 40

As an aircraft _______ the performance will reduce.

Answer 40

Climb

Question 41

Select the correct statement.

Select one:

a. Pressure reduces with altitude. Slowly initially, and then at a larger rate higher up
b. Pressure remains constant regardless of altitude because density and temeperature cancel each other out
c. Pressure reduces at a constant rate with altitude
d. Pressure reduces with altitude. Quickly initially, and then at a lower rate higher up

Answer 41

The correct answer is: Pressure reduces with altitude. Quickly initially, and then at a lower rate higher up

Question 42

Assuming that the temerature of the gas remains constant in these situations, select the correct statement(s).

Select one or more:

a. Increased volume means an decreased pressure
b. Increased density does not affect pressure
c. Increased density means an decreased pressure
d. Increased density means an increased pressure
e. Increased volume means an increased pressure
f. Increased volume does not affect pressure

Answer 42

The greater the density of the air, the greater the number of molecules there are colliding with the surface. This creates a greater force on a given area, meaning higher pressure.

The correct answers are: Increased density means an increased pressure, Increased volume means an decreased pressure

Question 43

In a flexible container that can expand or contract, is a gas substance. Select the correct statement(s) for the gas that is heated.

Select one or more:

a. Density increases slowly at first, and then faster at higher temperatures
b. Pressure decreases a lot
c. Density reduces
d. Pressure and density changes depend on the substance itself
e. Pressure increases
f. Pressure will remain equal to the surrounding air
g. Density remains the same

Answer 43

If the walls of our container disappeared, the high pressure hot air will expand until its pressure is equal to the surrounding colder air. Note this results in hot air having less density.

The correct answers are: Density reduces, Pressure will remain equal to the surrounding air