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Dimensions (mechanics)

Length, mass, time, or combinations of these quantities serving as an indication of the nature of a physical quantity. Quantities with the same dimensions can be expressed in the same units. For example, although speed can be expressed in various units such as miles/hour, feet/second, and meters/second, all these speed units involve the ratio of a length unit to a time unit; hence, the dimensions of speed are the ratio of length L to time T, usually stated as LT-1. The dimensions of all mechanical quantities can be expressed in terms of L, T, and mass M. The validity of algebraic equations involving physical quantities can be tested by a process called dimensional analysis; the terms on the two sides of any valid equation must have the same dimensions. See Dimensional analysis, Units of measurement

McGraw-Hill Concise Encyclopedia of Physics. © 2002 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



The dimensions of a physical quantity show by what factor the unit of the physical quantity is changed when the units of the quantities adopted as fundamental in the given system are altered. The dimensions are expressed by a monomial consisting of the product of various powers of the fundamental units, which are represented by generalized symbols; the exponents may be positive or negative integers or fractions. Thus, the dimensions of velocity are LT-1, where T represents the dimension of time and L the dimension of length. These symbols denote the units of time and length regardless of the specific size of the units. The units may be, for example, a second, minute, or hour and a meter or centimeter. In many cases, the dimensions permit the relations between corresponding quantities to be established.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.


The product of powers of fundamental quantities (or of convenient derived quantities) which are used to define a physical quantity; the fundamental quantities are often mass, length, and time.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
The findings of the study addressing the indicator wise dimensions of instructional planning and strategies for the capacity development of secondary school teachers may enlighten teacher education and capacity development.
Dimensions, unlike Google Scholar, clearly lists the sources of its data on its site.
For example, the volume of a rectangular box is found by measuring its length (often labeled x), width (y), and depth (z) which are the three dimensions of the object, whereas a 2D rectangle uses only its length and breadth.
As much as half of the machine stock added is commonly required to account for variations in the final dimensions. These final casting dimensions are affected by several issues.
Ghosheh will continue to lead the Dimensions Healthcare business as part of IMS Health.
(36,39) Given that no difference was observed in the coracoid base-glenoid distance (scapula dimension #7) between male and female scapula, the mean and variation of this measurement may be useful for surgeons to identify medial glenoid wear preoperatively with AP radiographs or intraoperatively using computer navigation.
Following the acquisition, Olim founder Tom Boser will take the role of CTO at Data Dimensions.
Hitherto we have been analyzing dimensions of unidimensional subsets, [F.sub.i], of a multidimensional set F.
The series of boot camps have been delivered in Six Dimensions' new training facility in New York, New York where the company's executive offices are also located.
Once any dimension has been degenerated, it is now harder to identify the primary key of the fact table.