Question

Which of the following sets alone cannot enter the list of fundamental quantities in any system of units?

(A) Length, mass, and speed
(B) Length, time, and speed
(C) Mass, time, and speed
(D) Length, time, and mass [1 Mark]

Answer 1

A fundamental quantity should be such that it does not depend on other quantities for its definition. Length, mass, and time are three of the most fundamental quantities in any system of units.

Speed is defined as the ratio of distance and time. Hence, length, time, and speed alone cannot be listed under fundamental quantities in any system of units because mass is missing from the set.

The other three sets given have length, mass, and time present in them either directly or indirectly in the form of a derived quantity.

Hence option B is correct.

[1 Mark]