Engineering system of units

In the English engineering system of units, force is treated as an additions independent dimension along with length, time, and mass. The pound force (lbr is defined as that force which accelerates 1 pound mass 32.1740 feet per seconc per second. Newton s law must here include a dimensional proportionality constant if it is to be reconciled with this definition. Thus, we write... 

This equation is the mathematical expression of the first law for a steady-state-flow process. All the terms are expressions for energy per unit mass of fluid in the SI system of units, energy is expressed in joules or in some multiple of the joule. For the English engineering system of units, this equation must be reexpressed to include the dimensional constant gc in the kinetic- and potential-energy terms ... 

In all of tlie energy-balance equations so far written, the energy unit is presumed to be tliejoule, in accord witlitlie SI system of units. For the metric engineering system of units, tlie kinetic- and potential-energy terms, wherever tliey appear, require divisionby the dimensional constant gc (Secs. 1.4 and 1.8). In tliis event Eq. (2.32a), for example, is written ... 

Prepare a table in which the rows are length, area, volume, mass, and time. Make two columns, one for the SI and the other for the American engineering systems of units. Fill in each row with the name of the unit, and in a third column, show the numerical equivalency (i.e., 1 ft = 0.3048 m). 

List the standard conditions for a gas in the SI, universal scientific, and American engineering systems of units. 

It is recognized at this time that the English Engineering System of units cannot be completely replaced by the International System (SI). Transition from the English system of units to SI will proceed at a rational pace to accommodate the needs of the profession, industry, and the public. The transition period will be long and complex, and duality of units probably will... 

Equation 4Ab can be used only if we can find a way to assign numerical values to the various symbols in it. We already have an expression for work, Eq. 4.1. It has the dimension of force times distance in SI its unit is the joule (lJ = N-m). In the English engineering system-of units, its unit is the foot-pound force, abbreviated ft lbf. 

An older unit of pressure, still in use, is the Torr, or mm Hg, representing the hydrostatic pressure exerted by a column of mercury i mm high. In the American Engineering system of units, pressure is measured in pounds of force per square inch, or psi. The relationship between the various units can be expressed through their relationship to the standard atmospheric pressure ... 

Historically the four most common engineering systems of units are... 

The Old English Engineering system of units uses pound (lb) for force, pound (lb) for mass, foot (ft) for length, and second or hour (s or hr) for time. Note that lb for force and lb for mass are not stipulated in this system of units. You have to be an astute, careful reader to distinguish which pound an author is using. This system of units has caused much confusion among scientists and engineers. 

This identification of Ibp and IbM brings us to the underlying cause of confusion concerning engineering systems of units namely, force is defined and not derived. Newton s second law states that... 

In other words, we have two independent variables and one dependent variable. We can specify the dimensions for any two variables, thereby allowing the third variable to become the dependent variable whose dimensions are derived from the dimensions of the other two variables. However, when we specify the dimensions of all three variables, we overspecify the equation. Thus in the Old English Engineering system of units Newton s second law has units of... 

What about go In the Old English Engineering system of units we... 

A. Klinkenberg, The American engineering system of units and its dimensional constant gc,... 

The code for clicking the Calculate BMI ( ) push button will be the same as that shown in Fig. 11.23. except that it is for calculating BMI as a function of input parameters, expressed in the American (engineering) system of units fFig. 11.24T... 

The dimensional constant = 32.2 ft lb /lby s is included here because these equations are still sometimes used with the English engineering system of units in SI units. 

The dimensional constant = 32.2 ft-lb /lbf-s is included here because these equations are still sometimes used with the English engineering system of units.) Since = (i /2)(dP/dx) (the minus sign has been dropped, it being understood that flow is in the direction of decreasing pressure), then... 

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