Units and Measurements in physics – 1

Units and measurements in physics is the first topic to understand well before moving on to the later parts of Class 11 physics. Dimensional analysis, which comes later in the study of units and measurements, is the core of the physical sciences. This is the first part of the series on units and measurements in physics.

Importance of Units and Measurements

Let us take the example of designing an aircraft. For this purpose, we have to calculate the forces on the developed model. The prototype model is developed and simulated in a laboratory, assuming the actual conditions, before finalizing the model. Here, for developing the prototype model, we need the units of measurement for drag forces, lift forces, moments, angular momentum, strength of materials, fluid physics constants, non-dimensional parameters such as the Reynolds number and Mach number, speed of sound, operational temperatures, factors of safety for various parameters, etc.

In the above design process, we require a lot of information involving thousands of parameters. Hence, for this purpose, we require a system of measurement and standard units. In their absence, we cannot make any prototype. Even for day-to-day use, we require units and measurements for food items, our shoe sizes, etc. Hence, units and measurements are a very essential part of our physics learning in day-to-day life.

Below is a typical indicative aircraft model for understanding the importance of units and measurement.

Introduction to Units and Measurements in Physics

It is an introductory class on Units and Measurements. There are various types of Units used for measurement. There are various types of Quantities that are used in our day to day life. Mass , Length and Time are the basic quantities measured in 3 different units as below. FPS, CGS, MKS systems use mechanical frame for measurements having only 3 base units . But the latest SI ( International System of measurements ) has 7 units of measurements.

1. FPS System – Foot, Pound, Second for measurement of Length, Mass and Time respectively.
2. CGS System – Centimeter, Gram, Second for measurement of Length, Mass and Time respectively.
3. MKS System – Meter, Kilogram, Second for measurement of Length, Mass and Time respectively.
4. SI System – Meter, Kilogram, Second for measurement of Length, Mass and Time respectively + Another four units are a) Ampere (A) for Electric Current , b) Kelvin (K) for temperature, c) Mole(mol) for substance, d) Candela (cd) for Luminous Intensity.

Two more units of measurement are also available in SI units in addition to above 7 units. They are plane angle $\mathit{\theta }$ and solid angle $\Omega$ .

As above presently the SI units are used for seven quantities as standard units of measurement. Here in this article Units and measurements, measurement units, measuring units, units of measurement, unit and what is the unit of measurement are discussed of physics class 11.

The particular video from channel maths&science by iitian on units and measurements is available at :

https://www.youtube.com/@mathsciencebyiitian

Units of Measurement list – SI Units

A table of SI units of Base Quantities with symbols, Names, Symbols, and Dimensions is given as below.

This is the first part of units and measurement . In the second part we will be discussing the Applications and the dimensional analysis. These articles on Physics Class 11 will be available at : https://mathsnscience.com/physics-class-11/

Conclusion

With this article , we made a start on understanding the importance of Units and Measurement in our day-to-day life applications. We will move forward to other parts of study on this topic in coming articles. For proper understanding of Science and Maths, or Maths and Science, or either way, maths and science together, we require a thorough understanding of this section.

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Best of luck to everybody.