Measurement Units And Dimensions In Physics Pdf Mechanics
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- Physical quantity
- 1.1: Dimensions and Units
- Dimensions of Physical Quantities
- Units of Measurement Physics Class 11 Download notes in pdf
Physics is a quantitative science, based on measurement of physical quantities. Certain physical quantities have been chosen as fundamental or base quantities. The fundamental quantities that are chosen are Length, Mass, Time, electric current, thermodynamic temperature, amount of substance, and luminous intensity.
In this article, we shall study the concept of dimensions of physical quantities and to find dimensions of given physical quantity. Dimensions of Physical Quantity:. The power to which fundamental units are raised in order to obtain the unit of a physical quantity is called the dimensions of that physical quantity. Dimensions of physical quantity do not depend on the system of units. Mass, length and time are represented by M, L, T respectively. Therefore, the dimensions of fundamental quantities are as follows:. Now electric current I and temperature K are also considered as fundamental quantities and using them the dimensions of electrical quantities are found.
1.1: Dimensions and Units
A physical quantity is a property of a material or system that can be quantified by measurement. A physical quantity can be expressed as the combination of a numerical value and a unit. For example, the physical quantity mass can be quantified as n kg , where n is the numerical value and kg is the unit. A physical quantity possesses at least two characteristics in common, one is numerical magnitude and other is the unit in which it is measured. For example, the recommended symbol for the physical quantity mass is m , and the recommended symbol for the quantity electric charge is Q. Subscripts are used for two reasons, to simply attach a name to the quantity or associate it with another quantity, or index a specific component e.
Physicists, like other scientists, make observations and ask basic questions. For example, how big is an object? How much mass does it have? How far did it travel? To answer these questions, they make measurements with various instruments e. The measurements of physical quantities are expressed in terms of units, which are standardized values. For example, the length of a race, which is a physical quantity, can be expressed in meters for sprinters or kilometers for long distance runners.
In order to be able to give an answer, we need certain measurable quantities as input - in the present case, the mass of the box and the height of a floor. Then, using our laws of physics, we will be able to produce another measurable quantity as our answer - here the amount of work needed. Of course, you could check this answer, and thus validate our physical model of reality, by measuring the quantity in question. The term we use to express this is, rather unfortunately, to say that physical quantities have a dimension - not to be confused with length, height and width. Anything that has a dimension can be measured, and to do so we use units - though there may be different units in which we measure the same quantity, such as centimeters and inches for length. When measuring the same quantity in different units, you can always convert between them - there are 2.
Dimensions of Physical Quantities
In engineering and science , dimensional analysis is the analysis of the relationships between different physical quantities by identifying their base quantities such as length , mass , time , and electric charge and units of measure such as miles vs. The conversion of units from one dimensional unit to another is often easier within the metric or SI system than in others, due to the regular base in all units. Dimensional analysis, or more specifically the factor-label method , also known as the unit-factor method , is a widely used technique for such conversions using the rules of algebra. Commensurable physical quantities are of the same kind and have the same dimension, and can be directly compared to each other, even if they are originally expressed in differing units of measure, e. Incommensurable physical quantities are of different kinds and have different dimensions, and can not be directly compared to each other, no matter what units they are originally expressed in, e.
The thumbnail image is of the Whirlpool Galaxy, which we examine in the first section of this chapter. Galaxies are as immense as atoms are small, yet the same laws of physics describe both, along with all the rest of nature—an indication of the underlying unity in the universe. In this text, you learn about the laws of physics. Galaxies and atoms may seem far removed from your daily life, but as you begin to explore this broad-ranging subject, you may soon come to realize that physics plays a much larger role in your life than you first thought, no matter your life goals or career choice. It operates on a vast range of scales involving length, mass, and time.
Units of Measurement Physics Class 11 Download notes in pdf
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