Atmospheric Composition and Pressure
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Questions and Answers

What is the approximate air pressure at the earth's surface?

  • 20.7 psi
  • 18.7 psi
  • 14.7 psi (correct)
  • 10.7 psi
  • What percentage of the atmosphere is composed of gases?

  • 80% by volume
  • 50% by volume
  • 100% by volume (correct)
  • 70% by volume
  • What is the highest altitude that civil aircraft would rarely exceed?

  • 30 000ft
  • 50 000ft
  • 45 000ft (correct)
  • 40 000ft
  • What is the layer of the atmosphere where all of the world's weather is contained?

    <p>Troposphere</p> Signup and view all the answers

    What is the direction of the change in atmospheric pressure with altitude?

    <p>Decreases with altitude</p> Signup and view all the answers

    Why do aircraft in English-speaking countries that have adopted the metric system still measure altitude in units of feet?

    <p>Due to historical reasons</p> Signup and view all the answers

    What is the primary reason for the decrease in air density as altitude increases?

    <p>Cooling of air</p> Signup and view all the answers

    What is the primary purpose of bimetallic strips and discs in various instruments and mechanisms?

    <p>To compensate for changes in ambient temperature</p> Signup and view all the answers

    What is the term for the height where the temperature stabilizes at about -56 °C?

    <p>Tropopause</p> Signup and view all the answers

    What is the main reason for the temperature coefficient of an altimeter?

    <p>Change of elasticity of the capsule material with change of temperature</p> Signup and view all the answers

    What happens to the elasticity of the capsule material when the temperature decreases at sea level?

    <p>It increases</p> Signup and view all the answers

    Why does air rise as it is heated?

    <p>Decreased density</p> Signup and view all the answers

    What is the effect of a decrease in temperature on the U-shaped bracket?

    <p>It causes the limbs to bend inwards</p> Signup and view all the answers

    What is the purpose of the International Standard Atmosphere (ISA)?

    <p>To correct for off-standard conditions</p> Signup and view all the answers

    What region of the atmosphere is characterized by rapid temperature decrease with altitude and turbulence?

    <p>Troposphere</p> Signup and view all the answers

    What is the purpose of the push rods in the altimeter's temperature compensating mechanism?

    <p>To connect the top capsule to the U-shaped bracket</p> Signup and view all the answers

    What is the abbreviation for the International Civil Aviation Organisation?

    <p>ICAO</p> Signup and view all the answers

    What would happen to the altimeter reading if the temperature decreases at sea level, without the temperature compensating mechanism?

    <p>It would over-read</p> Signup and view all the answers

    What is the effect of pressure change on the bimetallic U bracket strip?

    <p>It is not affected by the pressure change.</p> Signup and view all the answers

    What is the primary function of the pitot tube in a pitot static system?

    <p>To measure the ram pressure of the airstream.</p> Signup and view all the answers

    Where are the static ports typically located on an aircraft?

    <p>Along the sides of the fuselage.</p> Signup and view all the answers

    What is the purpose of the electric heaters in a pitot/static tube?

    <p>To prevent icing of the pitot tube.</p> Signup and view all the answers

    What is the name of the system that supplies pitot and static pressure for the instruments on an aircraft?

    <p>Pitot static system.</p> Signup and view all the answers

    What would happen to the bimetallic U bracket strip if there is an increase in ambient temperature?

    <p>It would expand and support the capsule movement.</p> Signup and view all the answers

    What happens to the air accelerating over the top of the wing surface as the aircraft approaches the speed of sound?

    <p>It approaches the speed of sound</p> Signup and view all the answers

    What is the result of the shock wave formation on the airflow?

    <p>Disrupted airflow</p> Signup and view all the answers

    What is the Critical Mach Number (Mcrit) of a commercial jet aircraft?

    <p>M.73</p> Signup and view all the answers

    Why is the Maximum Operating Mach Number (Mmo) value determined?

    <p>To avoid potential loss of control of a subsonic aircraft</p> Signup and view all the answers

    What is the purpose of the lubber mark on a Machmeter?

    <p>To show the Mcrit and Mmo</p> Signup and view all the answers

    What is the scale of a Machmeter marked in?

    <p>Decimal points of Mach 1</p> Signup and view all the answers

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