Scalar quantities
A physical quantity is something that can be measured. Scalar quantities only have a magnitude or size.
Examples of scalar quantities
Some examples of scalar quantities include:
- temperature – eg 10 degrees Celsius (°C)
- mass – eg 5 kilograms (kg)
- energy – eg 2,000 joules (J)
- distance – eg 19 metres (m)
- speed – eg 8 metres per second (m/s)
- density – eg 1,500 kilograms per metre cubed (kg/m3)
Calculations involving scalar quantities
Adding scalars
The sum of scalar quantities can be found by adding their values together.
Example
Calculate the total mass of a 75 kg climber carrying a 15 kg backpack.
75 kg + 15 kg = 90 kg
Subtracting scalars
Scalar quantities can be subtracted by subtracting one value from another.
Example
A room is heated from 12°C to 21°C using a heater. Calculate the increase in temperature.
21°C – 12°C = 9°C
