writing guide - 31.20

•express results in engineering notation

•use care with subscripts

+		∑Fx	= – T1 sin 60°						+ FR sin θ R =		0
+		∑Fy = –T1– T1 cos ( 60° )								+ FR cos θ	R = 0
		T1 sin 60°						T1 + T1 cos 60°
	FR = ----------------------						=	-----------------------------------	cos θ
		sin θ R								R
		sin 60°			=		sin θ	R	tan θ	R
	1--------------------------+ cos 60°						-------------- =
							cos θ	R
	tan θ R =		0.866
			----------------
			1 + 0.5
	θ R = 30°
	98 sin 60°		= FR sin 30°
	FR = 170N

(1)

(2)

sub (1) into (2)

31.11.5 Experimental Data

• When analyzing the results from an experiment there are a few basic methods that may be used,

Absolute difference - For example if the theoretical value is 105.8 and the measured value is 104.0 then you would say that "... the measured value was 1.8 below the theoretical value."

Percent difference - Avoid using this, but if must remember to assign a sign to the percentage value. For example if the theoretical value is 100 and the measured value is 50 then you would say that "... the measured value was 50% below the theoretical value." OR "... the theoretical value was 200% of the experimental value."

Mean and standard deviation - Useful for multiple data readings. Point by point - look at each point, and compare it to another.

writing guide - 31.21

• After data is presented, it should be discussed. In general a few good strategies

are,

-Discuss the fit between theory and measured. Explain differences in terms of hard facts and with numbers.

-Don’t make vague references to human or experimental error.

-Try to develop a conclusion about the quality of the experimental data.

-Make a recommendation about changes that would improve that data quality.

31.11.6 Result Summary

A results summary allows both the author and the reader a chance to review the resuls before a final conclusion. These should include the important results presented elsewhere in the report. It is best to use a graphical format such as a table or list.

31.11.7 References

•References help provide direction to the sources of information when the information may be questioned, or the reader may want to get additional detail.

•Reference formats vary between publication sources. But, the best rule is be con-

sistent.

•One popular method for references is to number them. The numbers are used in the body of the paper (eg, [14]), and the references are listed numerically at the end.

•Another method is to list the author name and year (eg, [Yackish, 1997]) and then list the references at the end of the report.

•Footnotes are not commonly used in engineering works.

•References on the internet should include a working web address, a description of the page (normally the page title), a date viewed and the page author if available.

31.11.8 Acknowledgments

• When others have contributed to the work but are not listed as authors we may

writing guide - 31.22

choose to recognize them.

• Acknowledgments are brief statements that indicate who has contributed to a

work.

31.11.9 Abstracts

An abstract is a brief summary of the results of the project. It us used by potential readers to determine if they are interested in reading a report. It should repeat a number of key details. An abstract should not omit key findings, as if it were an advertisement for a movie.

31.11.10 Appendices

Reports often include appendices to reduce bulk from the body. When putting material in an appendix it should stand alone and be referred to in the body of the report. It is customary to provide a summary of the results in the appendix, unless it is tutorial in nature. Examples of common appendices are given below.

sample calculations - these are redundant numerical calculations, or a prolonged derivation of equations. The body of the report has a summary of key assumptions,sample calculations and results. The calculations are often provided so that the reader may verify the calculations.

long tables of data - tables of numerical data are often put in appendices. Typically a sample of the table is included in the body for discussion purposes. These are often provided for the reader who wants to use the data beyond the uses in the report.

program listings - long listings of computer programs are often put in appendices. They are referenced in the body on the report near the algorithm/calculation/ method they implement. These listings are provided for readers who want to use the program.

multiple data graphs - multiple sets of data graphs are often put in appendices and summarized in a report body. The graphs are often provided so that the reader may use the graphs for verification or further analysis.

reviews of basic theory - these are often referenced in the body of the report for readers who may not have seen a topic previously. These are uncommon in student reports.

writing guide - 31.23

31.11.11 Page Numbering

- number all pages sequentially,

roman numerals starting from ‘i)’ on the first page arabic numerals starting from ‘1’ on the

-or, number pages by section. This is very useful for multi part manuals for example ‘4-7’ would be the 7th page in the 4th section

-if pages are blank label them ‘this page left blank’

-number sections sequentially with roman or Arabic numerals

31.11.12 Numbers and Units

-use engineering notation (move exponents 3 places) so that units are always micro, milli, kilo, mega, giga, etc. Avoid number formats such as ’0.00000456’

-use significant figures to round the numbers. For example a length of 0.345432in for a dimension measured with a ruler is ridiculous.

-units are required always

-greek symbols or the unit name spelled out

-take care to distinguish between frequency in hertz and radians/sec

-put a ’0’ before a point, 0.5 not .5

-

31.11.13 Engineering Drawings

The Padnos School of Engineering basic drawing requirements are summarized

below.

General Requirements

-a standard border

-a title block with a part name, employer/client/etc, designers name, date

of creation, units used, tolerances (unless noted on each dimension). Orthographic views

-three views unless axial symmetry allows fewer.

-the front view should be the most descriptive

-aligned correctly

-any hole/arc over 180 degrees must have center lines and marks

-blind holes made by drilling must have a drill point shown

-all parts must be manufacturable Dimensioning

-The location and size of each feature must be clearly defined

-critical assembly dimensions must be directly readable and not require