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

456 Chapter 14 Electronic Spreadsheets

where

Ddiameter of equivalent circular duct ( mm)

adimension of one side of the rectangular

duct ( mm)

bthe other dimension of the rectangular duct

( mm)

Using Excel, create a table that shows the relationship

between the circular and the rectangular duct, similar to the

one shown in the accompanying table.

where

Amonthly payments in dollars

Pthe loan in dollars

iinterest rate, e.g., 7, 7.5,... , 9

14.15. A Pitot tube is a device commonly used in a wind tun-

nel to measure the speed of the air flowing over a model.

The air speed is measured from the following equation:

where

Vair speed ( m/s)

Pddynamic pressure (Pa)

rdensity of air (1.23 kg /m

3

)

Using Excel, create a table that shows the air speed for

the range of dynamic pressure of 500 to 800 Pa. Use

increments of 50 Pa.

14.16. Use Excel to solve Example 7.1. Recall we applied the

trapezoidal rule to determine the area of the shape given.

14.17. We will discuss engineering economics in Chapter 20.

Using Excel, create a table that can be used to look up

monthly payments on a car loan for a period of five

years. The monthly payments are calculated from

AP ≥

a

i

1200

ba 1 

i

1200

b

60

a 1 

i

1200

b

60

 1

¥

V

B

2 Pd

r

Length of One Side of

Rectangular Duct (length a), mm

Length b 100 125 150 175 200

400 207

450

500

550

600

14.18. A person by the name of Sutterland has developed a

correlation that can be used to evaluate the viscosity of

air as a function of temperature. It is given by

where

mviscosity (N/s m

2

)

Ttemperature (K)

c 1 1.458  10

 6

c 2 110.4 K

Create a table that shows the viscosity of air as a func-

tion of temperature in the range of 0C (273.15 K) to

100 C (373.15 K) in increments of 5C. Also create

a graph showing the value of viscosity as a function of

temperature as shown in the accompanying spread-

sheet.

14.19.In Chapter 11, we explained the concept of windchill

factors. We said that the heat transfer rates from your

body to the surroundings increase on a cold, windy

day. Simply stated, you lose more body heat on the

cold, windy day than you do on a calm day. The wind-

chill index accounts for the combined effect of wind

speed and the air temperature. It accounts for the addi-

tional body heat loss that occurs on a cold, windy day.

The windchill values are determined empirically, and

a common correlation used to determine the windchill

index is

a

kg

m#s#K

1/2

b

m

c 1 T

0.5

1 

c 2

T

Interest Rate

Loan 7 7.5 8 8.5 9

10,000

15,000

20,000

25,000

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