C04 - Atmospheric Density

Question 1

Define Air Density?

Answer 1

A measurement of the mass of air contained within a specified volume.

Question 2

The greater the mass of air inside a volume, the ‘____’ the density?

Answer 2

Greater.

Question 3

What is the Lift Equation?

Answer 3

L = Cₗ x ½ pV² x A.

Question 4

What is the ISA Mean Sea Level Density?

Answer 4

1.225 kg/m³.

Question 5

Name three factors which affect Density?

Answer 5

• Temperature.
• Pressure.
• Humidity.

Question 6

As Temperature increases, the density of the air ‘____’?

Answer 6

Decreases.

Question 7

True or False. Rising air is a trigger for many weather phenomena?

Answer 7

True.

Question 8

As Temperature decreases, the density of the air ‘____’?

Answer 8

Increases.

Question 9

Cold denser air tends to ‘____’?

Answer 9

Sink.

Question 10

As air pressure increases, the density of air ‘____’?

Answer 10

Increases.

Question 11

As air pressure decreases, the density of air ‘____’?

Answer 11

Decreases.

Question 12

True or False. Pressure changes generally have a lower effect on the Air Density than Temperature changes?

Answer 12

False. Pressure has a greater effect.

Question 13

Define Humidity?

Answer 13

The amount of water vapour in the atmosphere.

Question 14

Increasing Humidity ‘____’ the Air Density?

Answer 14

Decreases.

Question 15

The Density of the air ‘____’ with Altitude?

Answer 15

Decreases.

Question 16

Density decreases with ‘____’ and it does so much faster at ‘____’ levels than at ‘____’ levels (3)?

Answer 16

• Altitude.
• Lower.
• Higher.

Question 17

In cold air density decreases more ‘____’ with height than in warm air?

Answer 17

Quickly.

Question 18

Low density reduces ‘____’ and decreases ‘____’ and therefore increases the ‘____’ distance and severely degrades the Aircraft’s ability to ‘____’ (4)?

Answer 18

• Lift.
• Engine Thrust.
• Take-off.
• Climb.

Question 19

Name the three least favourable conditions for Aircraft Performance?

Answer 19

• High Altitude.
• High Temperature.
• High Humidity.

Question 20

Define Density Altitude?

Answer 20

The Pressure Altitude corrected for Temperature Variation.

Question 21

Density Altitude is not used for Altimetry, it’s used to estimate ‘____’?

Answer 21

Aircraft Performance.

Question 22

What is the Density Altitude formula?

Answer 22

120ft per 1°C ISA Deviation.

Question 23

Define Relative Density?

Answer 23

Compares Actual Density against ISA Mean Sea Level Density as a percentage.

Question 24

What is the Relative Density at 40,000ft?

Answer 24

25%.

Question 25

What is the Relative Density at Mean Sea Level?

Answer 25

100%.

Question 26

What is the Relative Density at 22,000ft?

Answer 26

50%.

Question 27

What is the Relative Density at 10,000ft?

Answer 27

75%.