24.2 Aeroscience

24.2.2 State the International System (SI) unit used to express:

(a) length;

• metre (m)

(b) time;

• second (s)

(c) mass;

• kilogram (kg)

(d) temperature (K and ºC).

• kelvin (K)
  • when measured from absolute zero
   

• The degree Celsius (ºC)
  • when measured from the freezing point of water
   

24.2.4 State the derivation of the SI units for:

(a) force;

The SI unit for force is the newton (N), derived from the equation F = ma.

• is a push or pull resulting in a bodies change in motion.
• is defined as the force needed to accelerate one kilogram of mass at a rate of one metre per second squared

non-SI units

1 N = 0.22 pounds

(b) pressure;

The SI unit for pressure is the pascal (Pa), derived from force per unit area.

• is defined as the pressure of one newton per square metre (N/m²)

1 hectopascal (hPa) = 100 pascals

1013 hPa = 101300 pascals

1013 hectopascals is approximately equal to 1 atmosphere.