Fundamental Quantities in Physics

In physics, quantities are broadly classified into two categories: fundamental quantities and derived quantities. Understanding the difference between these is crucial for building a strong foundation in science.

Fundamental Quantities Defined

Fundamental quantities are those physical quantities that are independent of each other and cannot be expressed in terms of other physical quantities. They form the basic building blocks from which all other physical quantities can be derived. The International System of Units (SI) defines seven fundamental quantities:

• Length: Measures distance or extent in space. Its SI unit is the meter (m).
• Mass: Measures the amount of matter in an object. Its SI unit is the kilogram (kg).
• Time: Measures the duration of an event. Its SI unit is the second (s).
• Electric Current: Measures the rate of flow of electric charge. Its SI unit is the ampere (A).
• Thermodynamic Temperature: Measures the degree of hotness or coldness. Its SI unit is the kelvin (K).
• Amount of Substance: Measures the quantity of elementary entities. Its SI unit is the mole (mol).
• Luminous Intensity: Measures the power emitted by a light source in a particular direction. Its SI unit is the candela (cd).

Derived Quantities Explained

Derived quantities are those physical quantities that are dependent on fundamental quantities and can be expressed as a combination of two or more fundamental quantities. For example, speed is a derived quantity because it is calculated from length (distance) and time (speed = distance/time). Similarly, area is derived from length (length × width).

Analyzing the Options to Identify Non-Fundamental Quantity

Let's examine each option provided in the question:

• Mass: As discussed above, Mass is one of the seven fundamental quantities defined in the International System of Units. It is an independent quantity.
• Perimeter: Perimeter is the total length of the boundary of a two-dimensional shape. It is essentially a measure of length, but it's calculated by adding up multiple lengths. Therefore, Perimeter is derived from the fundamental quantity Length. It is not a fundamental quantity itself.
• Length: Length is explicitly listed as one of the seven fundamental quantities. It is a basic, independent physical quantity.
• Time: Time is also one of the seven fundamental quantities. It measures duration and is independent of other fundamental quantities.

Based on this analysis, Perimeter is the quantity that is not fundamental because it is derived from the fundamental quantity Length.