Engineering Fundamentals: An Introduction to Engineering, 4th ed.c

To enter a formula, select the cell where you want the result of the formula to be displayed. In

the Formula bar, then type the equal sign and the formula. Remember when typing your

formula to use parentheses to dictate the order of operation. For example, if you were to

type  100 5*2, Excel will perform the multiplication first, which results in a value of 10, and

then this result is added to 100, which yields an overall value of 110 for the formula. If how-

ever, you wanted Excel to add the 100 to 5 first and then multiply the resulting 105 by 2, you

should have placed parentheses around the 100 and 5 in the following manner: (100  5)*2,

which results in a value of 210. The basic Excel arithmetic operations are shown in Table 14.1.

Example 14.1 As we explained in the previous chapters, thermophysical properties of a substance, including

density, viscosity, thermal conductivity, and heat capacity, play a key role in engineering calcu-

lations. As discussed, the thermophysical property values represent information such as how

compact the material is for a given volume (density), or how easily a fluid flows (viscosity), or

how good a material is in conducting heat (thermal conductivity), or how good the material is

in storing thermal energy (heat capacity). The values of thermophysical properties are

commonly measured in laboratories at given conditions. Moreover, the values of thermophys-

ical properties of a substance generally change with temperature. The following example will

show how the density of standard air changes with temperature. The density of standard air is

a function of temperature and may be approximated using the ideal gas law according to

where

Pstandard atmospheric pressure (101.3 kPa)

Rgas constant and its value for air is 286.9

Tair temperature in Kelvin (K)

Using Excel, we want to create a table that shows

the density of air as a function of temperature in

the range of 0C (273.15 K) to 50C (323.15 K)

in increments of 5C.

Refer to the Excel sheets shown in

the accompanying figures when following the

steps.

1. In cell A1, type Density of air as a function
   of temperature.


2. In cells A3 and B3, type Temperature (C),
   Density (kg /m
   3
   ), respectively.


3. In cells A5 and A6, type 0 and 5 ,
   respectively.

a

J

kg#K

b

r

P

RT

14.3 Creating Formulas in Excel 423

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