91影视

First, we need to list the fundamental or basic physical quantities. Fundamental physical quantities are those that cannot be derived from other existing physical quantities. They serve as the foundation for the study of physics. There are seven basic physical quantities: 1. Length (symbol: L) - Measured in meters (m) 2. Mass (symbol: M) - Measured in kilograms (kg) 3. Time (symbol: T) - Measured in seconds (s) 4. Electric current (symbol: I) - Measured in amperes (A) 5. Temperature (symbol: 胃) - Measured in kelvin (K) 6. Luminous intensity (symbol: I_v) - Measured in candelas (cd) 7. Amount of substance (symbol: N) - Measured in moles (mol)

These quantities are called fundamental for a few important reasons: 1. They are all independent of each other and cannot be derived or reduced from other physical quantities. In other words, no combination of these quantities could be used to derive one of the others. 2. All other physical quantities in physics, also known as derived quantities, can be defined in terms of these fundamental quantities. For example, force can be defined as the product of mass and acceleration, with mass being a fundamental quantity and acceleration derived from the fundamental quantities of length and time. 3. They are used to define the units for all other derived quantities in a consistent manner. This system of units, called the International System of Units (SI), is built around these seven fundamental quantities. In conclusion, fundamental or basic physical quantities serve as the foundation for all other quantities in physics because they are independent of one another, form the basis for derived quantities, and are central to defining the units in the standard system of measurement.