Question

Which of the following is a derived physical quantity?
A. Mass
B. Velocity
C. Length
D. Time

Answer 1

Hint: The derived physical quantity can be expressed in terms of fundamental physical quantities. They are dependent on other physical quantities for measurement.
The fundamental physical quantity is also known as base physical quantities

Complete answer:
The number of physical quantities we measure using an instrument is very large; however, we do not need a large number of units for measurement because many physical quantities are linked with other physical quantities and it can be expressed with the help of fundamental physical quantity.
Let us understand the fundamental physical quantity first; it is those physical quantities that are not dependent on any other physical quantities. It neither be obtained or derived from any other physical quantities nor simplified any further. The fundamental physical quantity is also known as base physical quantities. There are seven base quantities in the international system of units that are mass, length, time, temperature, electric current, luminous intensity, and the amount of substance.
The physical quantities that are derived from the two or more than two fundamental physical quantities are termed as derived units. They are dependent on other physical quantities for measurement.
By going through the options given in the question, we know that the mass, time and length are fundamental physical quantities.
We know that the velocity of a body is equal to the rate of change of position of the body and it can be expressed as:
Velocity $ = \dfrac{{{\rm{Change}}\;{\rm{in}}\;{\rm{position}}}}{{{\rm{Change}}\;{\rm{in}}\;{\rm{time}}}}$
We know change in position is length and change in time is time. So we can say that velocity is derived from two fundamental physical quantities.

So, the correct answer is “Option B”.

Note:
Other examples of derived physical quantities are acceleration, force, momentum, work, volume etc. Also, the units associated with the fundamental quantities are called fundamental units and the set of fundamental and derived units is known as a system of units.