Use adaptive quiz-based learning to study this topic faster and more effectively.

# Estimation of common physical quantities

Estimation involves finding a value that is reasonably close to the true value of a physical quantity without any measurement. It is used to check any measured or reported values.

If you know that the mass of an adult is about $70\text{ kg}$, you can estimate that the mass of a bag of apples must be less than $70\text{ kg}$.

Some values of common physical quantities are as follows:

Physical quantity Value
Average mass of an adult $70\text{ kg}$
Room temperature $300\text{ K}$
Average height of an adult $1.7\text{ m}$
Household microwave power consumption $900\text{ W}$
Energy in a teaspoon of sugar $70\text{ kJ}$

Instead of giving a precise numerical value, it is often sufficient to estimate the order of magnitude of a quantity. This involves just stating the value of ten raised to the appropriate power.

The diameter of an atomic nucleus is around $10^{-12}\text{ m}.$

The sun has a mass of roughly $10^{30}\text{ kg}.$