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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)
(d) mass;
- kilogram (kg)
(e) volume;
- cubic metre (m³)
(f) temperature;
- kelvin (K)
- when measured from absolute zero
- The degree Celsius (ºC)
- when measured from the freezing point of water
(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.
Gravitational Force (g)
- is the force of attraction between two objects due to their masses and the distance between them.
- the bigger the object, and the closer the distance, the bigger the force.
- Earth has a value of 9.81 m/s² at its surface.
- The Moon has a value of 1.62 m/s²
Weight (W)
- the force produced by gravitational attraction between masses.
- Weight = mass x gravity (W = mg)
- because the earth is larger than the moon, 1kg of mass is heavier on the earth than on the moon.
(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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