# Unit and measurement important questions

## Q.1.  Will it be possible to use one and the same unit to measure physical quantities?

Ans : The answer of this question is mostly scientific. If it is possible to express all the physical quantities in terms of single physical quantity then definitely we can use one unit to express all the physical quantities. But physical quantities may be expressed as the physical quantity raised to the power some number.
This number could be real, imaginary or complex. For instance Length, breadth and height all can be expressed in terms of length. Length = m Area = m^2
Volume = m^ 3

## Q.2. What will happen if physical quantities are not universally accepted?

Ans : If the physical quantities are not universally accepted then different countries and even individual persons will use their own considered physical quantity for any measurement. In this way there may be a contradiction in the measurement of same quantity. So a system of physical quantities and their SI units have been defined and instructed to use the same one, world wide to avoid the contradictions in different measurements?

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## Q.3. What are the differences between Fundamental and Derived physical quantities ?

Ans : Fundamental Physical quantities are self defined. These quantities don't need any other physical quantities to derive themselves.

For example : Length, mass, time, luminous intensity, temperature, electric current and amount of Substance are fundamental (Base) physical quantities.

On the other hand, derived physical quantities are defined in terms of fundamental physical quantities. As velocity is defined in terms of length and time ( in terms of two fundamental physical quantities ).

Other derived physical quantities are : Acceleration, force, impulse, momentum, angular momentum, moment of inertia, energy , etc.