Question

Which of the following is not a fundamental quantity?
A. mass
B. length
C. velocity
D. time

Answer 1

Fundamental quantities are the phenomena which can be measured uniquely, which are the basic quantities and do not depend on any other quantities. These quantities are also essential to form any other quantities which are not fundamental quantities.

Complete answer:
We know, physical quantities are the phenomena which can be measured by the use of instruments or by calculation and fundamental quantities are the quantity of any physical measurement which are uniquely measured. Fundamental quantities are the basic quantities and do not depend on any other quantity. These quantities are also essential to form any other physical quantities which are not basic quantities.

There are seven fundamental quantities that have been recognized internationally in the science world. These are:
-Length
-Mass
-Time
-Electric current
-Thermodynamic temperature
-Amount of substance
-Luminous intensity
Also there are quantities which are treated as basic or fundamental quantities but do not have any dimension, these are:
-Plane angle
-Solid angle

All other quantities that are derived from these quantities are called Derived quantities. A few examples of which are, acceleration- which is the ratio of length and square of time, hence made of two basic quantities namely time and length. Force- product of mass and acceleration. Basic quantities are mass, time and length. And so many more examples are there. So, we have here mass, length and times are the basic quantities given in the question. But velocity is a derived quantity which is derived from the basic quantity length and time.

Hence, option A, B and D all are correct.

Note: To solve problems around basic or fundamental quantities one must remember all the basic quantities first. From there it can be easily solved whether it is dimension related problem or problem relating to units of any physical quantity. Dimension of any physical quantity is basically the mathematical expression which expresses how it is related to the basic quantities.