1.1 Physical and Non-Physical Quantities

1.1 Physical and Non-Physical Quantities

We describe various natural phenomena, events, and human behaviour using features and terms such as love, affection, fear, wisdom, beauty, length, volume, density, time, and temperature. Some of these can be measured directly or indirectly using tools and instruments. For example:

• Length of an object using a ruler.
• Time duration of an event using a clock.
• Temperature of a body using a thermometer.

These are called physical quantities. The foundation of physics rests upon physical quantities through which the laws and principles of physics are expressed.

Other quantities, such as love, affection, fear, wisdom, and beauty, cannot be measured using tools and instruments. They often pertain to the perception or interpretation of the observer. They can be described or compared qualitatively using pre-determined criteria, indices, or survey techniques. Non-physical quantities mostly help us understand and analyse human behaviour, emotions, and social interactions.

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Quick Quiz: Is a non-physical quantity has dimensions?

Table 1.1: Physical vs Non-Physical Quantities