Earth Science Laboratory
A. Review of Common Types of Map Scales
2. Representative Fraction (R.F.): An R.F. scale is aratio, or fraction, that expresses the mathematical relationship betweenMAP and LAND, such as1 : 24,000
3. Graphic Scale: The graphic scale is a bar chart or'ruler' that is drawn at the bottom of a topographic map. This is the scalethat you should use when asked to measure distances on the map. BeCareful: Note that the zero mark is not located at the left end ofthe graphic scale. For your convenience, the graphic scale extends to theleft of the zero mark to indicate fractions of units, such as 1/10 of amile. You may measure distances by marking off the 2 end points on theedge of a sheet of paper and aligning the edge of the paper against thegraphic scale (make sure one of your marks is on the zero).
B. CONVERTING A VERBAL SCALE TO AN R.F.
1 millimeter (mm) = 0.0393701 inch (in). Millimeter (mm) is a unit of Length used in Metric system. Centimeters (cm): 0.1: 0.2: 0.3: 0.4: 0.5: 0.6: 0.7: 0.8: 0.9: 1.0: 1.1: 1.2: 1.3: 1.4: 1.5: 1.6: 1.7: 1.8: 1.9: 2.0: 2.1: 2.2: 2.3: 2.4: 2.5: 2.6: 2.7: 2.8: 2.9: 3.0. To convert 2 in to cm multiply the length in inches by 2.54. The 2 in in cm formula is cm = 2. 2.54. Thus, for 2 inches in centimeter we get 5.08 cm. Conversion Table: fractional inches, decimal inches, mm This page was written by Steven J. DeRose (via Ruby) on 2003-03-28, and was last updated on 2003-03-28. This table of equivalents should be useful for drill bit sizes, wrench and socket sizes, etc.
MAP SCALES & UNITS
This handout was designed to help you understand the relationships betweendifferent map scales, map units, distance, and area. You should understandthe logic behind how these are used and how they should appear on realtopographic maps. On your upcoming lab exam, you should also be able toconvert one type of map scale into another, and calculate size differences(scale factor, area factor) between different maps.
A. Review of Common Types of Map Scales
All map scales are an expression of the numerical relationship betweenthe MAP and the LAND that is represented. The MAP unit is always mentionedfirst.
1. Verbal Scale: The verbal scale is just a sentence statingthat '1 Map Unit = X Land Units'. For reasons of convenience, amixture of units is commonly used, such as
1 inch = 1 mile
However, there are NO requirements that the units must bedifferent! The expression '1 inch = 63,360 inches' is stilla verbal scale. A mixture of map and land units makes the verbal scaledifficult to compare between different maps - it must be converted firstto a Representative Fraction (see below).
2. Representative Fraction (R.F.): An R.F. scale is aratio, or fraction, that expresses the mathematical relationship betweenMAP and LAND, such as
which means '1 map unit is equivalent to 24,000 land units.' Avid pro tools 11. Because an R.F. carries no units (inches, centimeters, etc.), it meansthat the R.F. scales can be compared between different maps. Convertingan R.F. scale to a verbal scale is very easy; simply select ONE unit andapply it to BOTH map and land numbers. The above example can be writtenas a verbal scale as '1 inch = 24,000 inches' or '1 meter = 24,000meters,' etc. (Note: YOU CANNOT MIX UNITS in an R.F.! Doing so willchange the numerical relationship of the R.F.)
3. Graphic Scale: The graphic scale is a bar chart or'ruler' that is drawn at the bottom of a topographic map. This is the scalethat you should use when asked to measure distances on the map. BeCareful: Note that the zero mark is not located at the left end ofthe graphic scale. For your convenience, the graphic scale extends to theleft of the zero mark to indicate fractions of units, such as 1/10 of amile. You may measure distances by marking off the 2 end points on theedge of a sheet of paper and aligning the edge of the paper against thegraphic scale (make sure one of your marks is on the zero).
B. CONVERTING A VERBAL SCALE TO AN R.F.
When converting a verbal scale to an R.F., the strategy is to convertfrom mixed units (verbal scale) to one unit (R.F.). That is thebasic difference between these two types of map scales.
Example:
If your verbal scale is '1 inch = 1 mile' how is this expressedas an R.F.?
Solution:
1. Decide which ONE unit to convert to: To becomean R.F., both the map and land units (now 2 different types) must be thesame. You have 2 choices to choose from: you can either convert milesto inches or inches to miles.It is usually easier to convertfrom a larger to a smaller unit ('how many inches are in a mile?' iseasier to handle than 'how many miles are in an inch?'). So, we will thenconvert the '1 mile of land' to 'X number of inches'.
2. Eliminate the unwanted unit by multiplication:One of the basic rules of algebra is that any number or unit divided byitself equals 1. If you started with miles and wanted to get rid of milesand end up with inches, how do you do this?
First, get rid of 'miles' by multiplying it by a fraction that contains'miles' in the denominator, and an equivalent number of smaller unitsin the numerator. You may not know how many inches there are in a mile,but you should know that there are 5,280 feet in a mile. This will getrid of miles, but will leave you with 'feet' which is still not the sameunit as the Map Unit (inches). To get to inches, get rid of 'feet' by multiplyingby a fraction that contains 'feet' in the denominator and the equivalentnumber of inches in the numerator:
(1 mile) | (1 foot) | = 63,360 inches |
Translate Inches To Feet
Now that the original land unit '1 mile' has been converted to 63,630inches, both the map and land units are now the same type, and the R.F.is written simply by deleting the units and substituting a colon for theequal sign:
1 inch = 63,360 inches
1 : 63,360
There is no 'right' way or 'wrong' way to multiply - you must decidehow to set up the fractions so that the units you don't want get canceled,and the unit you do want ends up as your answer.
C. CONVERTING AN R.F. TO A VERBAL SCALE
Converting an R.F. to a verbal scale is usually much easier than thereverse. Twitterrific 5 1 0 download free. By definition, an R.F. means that both the map and landunits are the same, so you can choose any ONE unit: 1 : 24,000can be '1 cm = 24,000 cm' or '1 inch = 24,000,'so longas you do not use two different units.Remember, there is NOREQUIREMENT that a verbal scale must use different units!
D. COMPARING SCALES AND AREAS BETWEEN DIFFERENT MAPS
One of the major advantages of using the R.F. (Representative Fraction)scale is that it allows you to directly compare the sizes of objects betweendifferent maps. Because the R.F. eliminates the use of specific units (suchas inches, feet, miles, etc.), there are no complicated conversions needed.
Comparing R.F. Scales Between Different Maps
Simply divide the larger map scale by the smaller one to get the SCALEFACTOR:
SCALE FACTOR = | R.F. of Map B | 1:10,000 | = 5 |
Relationship Between Scale & Area
A map scale measures distance, which is a one-dimensionalunit. Area is a 2-dimensional quantity, calculated by measuring'Length X Width.' Note that when a map scale is changed by a certainnumber factor, the area changes by the square of that number. In otherwords, if the scale is 2 times larger, the area becomes 4 times larger;if the scale is 5 times larger, the area becomes 25 times larger:
The above map shows a land area of 500 feet X 500 feet = 250,000 square feet. |
|
Note that although both maps are the same size, Map A covers 500 unitsof distance versus only 100 units for Map B. But, Map A (500x500 = 250,000sq. ft.) covers 25 TIMES the AREA of Map B (100x100 = 10,000 sq.ft/).
So, the relationship between the SCALE FACTOR and AREA FACTOR is:
AREA FACTOR = (SCALE FACTOR)2
Translate Inches To Millimeters
Copyright © 1996 by William K. TongThis calculates either way (feet/inches to decimal feet or vice versa).
Inches can have a fraction (3 1/4) or decimal (3.25 or 3,25).
Inches can have a fraction (3 1/4) or decimal (3.25 or 3,25).
Inch | Decimal of a Foot |
---|---|
1 inch | 0.0833 |
2 inches | 0.167 |
3 inches | 0.250 |
4 inches | 0.333 |
5 inches | 0.417 |
6 inches | 0.500 |
7 inches | 0.583 |
8 inches | 0.667 |
9 inches | 0.750 |
10 inches | 0.833 |
11 inches | 0.917 |
12 inches | 1.000 |
Translate Inches To Centimeters
To convert further, 1/8″ is almost 1/100th of a foot. | ||
---|---|---|
1″ | = | 0.08 |
1 1/8″ | = | 0.09 |
1 1/4″ | = | 0.10 |
1 3/8″ | = | 0.11 |
1 1/2″ | = | 0.13 |
1 5/8″ | = | 0.14 |
1 3/4″ | = | 0.15 |
1 7/8″ | = | 0.16 |
2″ | = | 0.17 |
Translate Inches To Mm
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Translate Inches To Pixels
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Translate Tab 2 0 8 Inches =
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