Difference between Fundamental Quantities and Derived Quantities
Before we go deeper into the article, we will look at a table showing the difference between fundamental quantities and derived quantities. We will also see another table showing the difference between fundamental units and derived units.
| Fundamental Quantities | Derived Quantities | |
| 1. | They are generally accepted quantities | They are just accepted |
| 2. | FQ is based on an international system | They are formulated from an international system |
| 3. | They can stand alone | They cannot stand alone |
| 4. | FQ have direct calculations | Their calculations are arrived at |
| 5. | They are basic units of measurement | They are not basic units of measurement |
Explanation
Fundamental quantities and derived quantities are fundamental concepts in physics that help describe and measure various aspects of the physical world. In this article, we will explore the difference between these two types of quantities, their characteristics, examples, and their significance in scientific measurements.
Fundamental quantities, also known as base quantities, are basic physical quantities that we cannot define in terms of other quantities. They are the building blocks upon which we can derive other quantities. On the other hand, we obtain derived quantities by combining fundamental quantities using mathematical formulas and equations.
Characteristics of Fundamental Quantities
Fundamental quantities are the foundation of measurement, while derived quantities are due to the combinations of these fundamentals in various ways. Here is a brief table highlighting the differences between fundamental quantities and derived quantities in physics:
| Characteristic | Fundamental Quantities | Derived Quantities |
|---|---|---|
| Definition | Basic, independent, and cannot be expressed in terms of other quantities. | Derived from combinations of fundamental quantities through mathematical expressions. |
| Examples | Length (L), Mass (M), Time (T) | Speed (v), Force (F), Energy (E) |
| Independence | Independent of other quantities. | Dependent on fundamental quantities in their definitions. |
| Units | Have their own distinct units (e.g., meters, kilograms, seconds). | Units are derived based on combinations of fundamental units. |
| Measurement Tools | Measured directly using basic measuring instruments. | Often measured indirectly using formulas and derived equations. |
| Importance in Formulas | Serve as the building blocks for defining other quantities. | Act as variables in formulas expressing physical relationships. |
A. Base Units
We associate fundamental quantities with base units, which are the standard units of measurement for those quantities. In the International System of Units (SI), there are seven base units: meter (m) for length, kilogram (kg) for mass, second (s) for time, ampere (A) for electric current, kelvin (K) for temperature, mole (mol) for the amount of substance, and candela (cd) for luminous intensity.
B. Independence
The fundamental quantities are independent of each other. They represent distinct physical properties that are not reducible to other quantities. For example, length and time are fundamentally different and we cannot express it solely in terms of each other.
Characteristics of Derived Quantities
A. Formulas and Equations
Derived quantities are derived from fundamental quantities through mathematical formulas and equations. These formulas describe the relationship between the fundamental quantities and provide a way to calculate the derived quantity. For example, we can obtain speed by dividing the distance travelled by the time taken, using the formula:
speed = distance / time.
B. Dependence on Fundamental Quantities
Derived quantities depend on the values of fundamental quantities. Changes in the values of fundamental quantities will affect the derived quantities that depend on them. For example, we obtain the force acting on an object from the mass of the object and its acceleration. If either the mass or the acceleration changes, the force will also change accordingly.
Measurement and Units
A. Measurement of Fundamental Quantities
We measure fundamental quantities directly by using appropriate measuring instruments and techniques. For example, we can measure the length by using a ruler or tape measure. Additionally, we can measure mass by using a balance or scale. While for time, we can use a stopwatch or clock for measurement. We can express these measurements in the corresponding base units.
B. Measurement of Derived Quantities
We measure derived quantities indirectly by combining measurements of fundamental quantities using the appropriate formulas. For example, to measure speed, you would measure the distance travelled and the time taken, and then use the formula speed = distance / time to calculate the speed. We derive the units of derived quantities from base units.
Examples of Fundamental Quantities
A. Length
The length is a fundamental quantity that measures the extent of a one-dimensional object. We measure it in meters (m) and we often use it to describe distances or sizes.
B. Mass
The mass is a fundamental quantity that measures the amount of matter in an object. We measure it in kilograms (kg) and we commonly use it to describe the heaviness or inertia of an object.
C. Time
Time is a fundamental quantity that measures the sequence of events or the duration between events. The form of measurement for time is in seconds (s). It plays an important role in various scientific calculations and observations.
D. Electric Current
An electric current is a fundamental quantity that measures the flow of electric charge. We measure it in amperes (A) and is essential for understanding and analyzing electrical circuits and devices.
E. Temperature
The temperature is a fundamental quantity that measures the hotness or coldness of an object or a system. The form of measurement is in kelvin (K). Additionally, we use it in a wide range of scientific, industrial, and everyday applications.
F. Amount of Substance
The amount of substance is a fundamental quantity that measures the number of particles (atoms, molecules, ions, etc.) in a sample. We measure it in moles (mol). It is significant in chemical reactions and stoichiometry calculations.
G. Luminous Intensity
We also have luminous intensity which is a fundamental quantity that measures the power of light emitted by a source in a particular direction. The si unit of luminous intensity is in candelas (cd) and is important in lighting design and photometry.
Examples of Derived Quantities
A. Speed
Speed which is a derived quantity that measures the rate of change of distance with respect to time. We calculate it by dividing the distance travelled by the time taken. Additionally, it is units are meters per second (m/s) or kilometres per hour (km/h).
B. Acceleration
Acceleration is a derived quantity that measures the rate of change of velocity with respect to time. The form of calculation is by dividing the change in velocity by the time taken. Its units are meters per second squared (m/s²) or kilometres per hour squared (km/h²).
C. Force
Force is a derived quantity that measures the interaction between two objects and their tendency to accelerate. It is calculated by multiplying mass by acceleration and is expressed in units called newtons (N).
D. Energy
Energy is a derived quantity that measures the ability to do work or cause change. It is calculated by multiplying force by distance and is expressed in units such as joules (J) or calories (cal).
E. Power
Power is a derived quantity that measures the rate at which work is done or energy is transferred. It is calculated by dividing work or energy by time and is expressed in units like watts (W) or horsepower (hp).
Conversion between Fundamental and Derived Quantities
A. Conversion Factors
The conversion between fundamental and derived quantities is possible through conversion factors. Conversion factors are ratios that relate the units of different quantities. By multiplying or dividing by appropriate conversion factors, we can convert between different units of measurement while maintaining the same value.
B. Dimensional Analysis
Dimensional analysis is another method we use to convert between fundamental and derived quantities. It involves analyzing the dimensions or units of the quantities involved in a calculation and ensuring that they are consistent. By cancelling out matching units and manipulating the equations, we can convert between different quantities.
Importance of Fundamental and Derived Quantities
A. Application in Science and Engineering
Fundamental and derived quantities form the basis for scientific understanding and engineering applications. They provide a standardized system for measurement, allowing researchers and engineers to communicate and reproduce experiments and calculations. Without these quantities, it would be challenging to quantify and analyze physical phenomena accurately.
B. Standardization and Consistency
Fundamental quantities and their associated base units provide a standardized framework for measurement. They ensure consistency and uniformity in scientific research, technological advancements, and international trade. Standardization facilitates collaboration and comparison of results across different fields of study and countries.
Conclusion
In conclusion, fundamental quantities and derived quantities are essential concepts in physics and measurement. Fundamental quantities are independent base quantities that cannot be defined in terms of other quantities, while derived quantities are obtained through mathematical formulas and depend on fundamental quantities. Both types of quantities play a crucial role in scientific research, engineering applications, and everyday life. Understanding the difference between fundamental and derived quantities helps us comprehend and quantify the physical world more accurately.
FAQs
- Can derived quantities have negative values? Yes, derived quantities can have negative values. Negative values indicate a direction or opposite effect compared to positive values. For example, negative acceleration represents deceleration or slowing down.
- What are the SI units for fundamental quantities? The SI units for fundamental quantities are meter (m) for length, kilogram (kg) for mass, second (s) for time, ampere (A) for electric current, kelvin (K) for temperature, mole (mol) for the amount of substance, and candela (cd) for luminous intensity.
- How are derived quantities used in real-life applications? Derived quantities are used in various real-life applications, such as calculating speeds and distances in transportation, determining forces in structural engineering, measuring energy consumption, and analyzing electrical circuits.
- Are there any fundamental quantities that are not derived quantities? No, all fundamental quantities are not derived quantities. Fundamental quantities are the basic building blocks, and they cannot be expressed in terms of other quantities.
- Can you give an example of a derived quantity that depends on multiple fundamental quantities? Yes, pressure is an example of a derived quantity that depends on multiple fundamental quantities. Pressure is calculated by dividing the force by area, where force depends on mass and acceleration, while area depends on length squared.
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