61. 2) What is absolute humidity?
1.The temperature to which humid air must be cooled at constant pressure to become saturated.
2.The actual amount of the water vapour in a mixture of air - water.
3.The ratio of the water vapour actually present in the atmosphere to the amount that would be present if the air were saturated at the prevailing temperature and pressure.
The correct answer is
the actual amount of water vapour in a mixture of air and water
Thanks for notifying, We will check the answer and let you know and do the necessary changes
62. With ISA conditions, what is the temperature at 30,000ft ?
A. Troposphere, Tropopause, Ionosphere, Exosphere
B.Stratosphere, Ionosphere, Exosphere Tropopause
C. Troposphere, Stratosphere, Ionosphere, Exosphere
this is a copy of the question and I don't think it has the correct answers for this question. Answers are not related
Thanks for notifying. it is corrected
63. 4) An aircraft travels at a constant speed of 800 km/h for 30 minutes. How far it would have traveled in 30 minutes?
In an hour it will travel 800 km. So in half an hour(30 min) it would travel a distance of 400 km. The answer should be 400 km.
64. The purpose of a patch cord used with an OTDR is
a. to compensate for any contraction of the Fiber optic cable during test.
b. to overcome the dead zone problem caused by reflection at OTDR launch connector.
c.to attenuate OTDR output power which could cause damage to the cable under test.
Optical Time-Domain Reflectometer (OTDR) is an optoelectronic instrument used to characterize an optical fiber. A patch cord is a length of cable, with connectors on the ends. At the same time, when the faults are masked in the length close to the OTDR is called "dead zone".
The patch code is used to overcome the dead zone problem.
65. Question from: Prathan
Radiant heat of a body, heated from a radiant source is
a. inversely proportional to the square of the distance.
b. proportional to distance.
c. inversely proportional.
Radiant heat, radiates out from a source, warm objects rather than the air. For example the heat you feel from a fire without touching it is due to radiant heating. As you move away the intensity of heat reduces. Further you move lesser you feel the heat. This is defined with the inverse-square law.
The Answer : A. inversely proportional to the square of the distance
66. Question from: Prathan
If heat is constant, and if pressure increases on a liquid what will the volume do?
According to Boyle's law, as the pressure increases the volume decreases when the system is at a constant temperature. The Boyle's law is only applicable for gases. Here the question is about the liquid, and liquids are usually incompressible. So the volume remains the same irrespective of pressure variation.
The answer is: Volume remains the same
67. If a tuning fork is struck and held close to the ear and slowly rotated about the vertical axis in one rotation how many times is there no sound?
In mediums which are fluid (e.g., gases and liquids), sound waves can only be longitudinal. So when the tuning fork is held near ear, sound can be heard, but when it moved up or down, the sound cannot be heard. In one rotation tuning fork moves up and back to ear and then down and back to ear. The sound cannot be heard twice ( one, when the fork is above the ear and second time when the fork is bellow the ear). Sound can heard only when the fork is near the ear.
68. Vortex generators
a. move the transition point forward.
Why is this right? Vortex generators don't delay the appearance of the transition point? Please advice
Laminar boundary layers are uninterrupted smooth flow that reduces drag. At the same time they are very fragile and can easily separate from the wing surface when they encounter an adverse pressure gradient.
Whereas turbulent flow speeds up the airflow and gives it more forward momentum. As a result the turbulent boundary layer stays with the surface much longer before it separates from the surface, which in turn delays the stall.
Vortex generators energize the airflow and generate a turbulent boundary layer at early stage whereby transition point move towards the leading edge.
69. Why cabin window shades have to be pulled up before takeoff and landing?
Answer by: Suganthan Nadarajah
This is to provide better visibility in case of accident. The first aiders can see if there is any fire in the cabin, and if any seen, can direct the passengers to use the safe exit passage.
70. Why there are no parachutes on passenger aircraft?
Answer by: Jeshan Mishel
Cost Factor - parachutes on board equate to increase weight and hence resulting in increase fuel consumption and maintenance.
Storage - Large number of parachute storage in a limited spaced aircraft may pose a problem.
Temperature - Evacuation at altitudes above 40,000 feet with temperatures between -45 0C and -60 0C is not compatible for human survival.
Knowledge - Not every passenger is comfortable with jumping off planes and handling parachutes.
Practical issues - Evacuating 300 people of varying ages off a plane may be challenging.
Air crashes are rarely seen in recent times due to the advanced technology and effective safety measures in place. It is apparently 25 times safer than any other form of transport.
There are many reasons: