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12.2 Definitions, Terminology, Units and Abbreviations

12.2.2 State the International System (SI) and ICAO units used to express:

(a) distance;

  • metre (m)


(b) time;

  • second (s)


(c) velocity;

  • metres/second (m/s)
  • nautical miles/hour (kts)


(d) mass;

  • kilogram (kg)


(e) volume;

  • cubic metre (m³)


(f) temperature;

  • kelvin (K)
  • The degree Celsius (ºC), a derived SI unit, is far more common.


(g) altitude.

  • feet (ft)


12.2.4  Define and where appropriate show the relevant relationships between:

(a) mass, weight and gravitational force (g);

Mass (m)

  • the amount of matter in an object. 
  • 1kg of mass on the earth is the same as 1kg of mass on the moon.


Weight (W)

  • the force produced by gravitational attraction between masses.
  • Weight = mass x gravity (W = mg)
  • the 1kg of mass is heavier on the earth than on the moon.


Gravitational Force (g)

  • a force acting towards the centre of an object.
  • the bigger the object, the bigger the force.


(b) inertia;

  • A property of matter by which it continues in its existing state of rest or uniform motion in a straight line.
  • More mass = more inertia.
  • Newton's first law states that every object will remain at rest or in uniform motion in a straight line unless compelled to change its state by the action of an external force.
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