Idaho Society of Professional Engineers
Friday Update – 03/02/07
UPCOMING EVENTS:
• March 10, 2007 – State
MATHCOUNTS Competition –
Boise State University, Boise
• March 22 & 23, 2007 –
ISPE 2007 Annual Meeting –
Oxford Suites, Boise
• May 11, 2007 – National
MATHCOUNTS Competition –
Convention Center, Fort Worth, Texas
• May 11, 2007 – ISPE
Southwest Chapter Spring Fundraiser Golf Tournament
IT’S
NOT TOO LATE TO REGISTER FOR THE ISPE 2007 ANNUAL MEETING!
Program and registration information can be found on the
ISPE web site.
Please participate in the
Engineering Income and Salary Survey by March 31, 2007! All participants
will be entered into a drawing to win a Video iPod!
MATHCOUNTS PROBLEM OF THE WEEK
Can you solve this MATHCOUNTS problem? The answer will appear in next week's
edition of the Friday Update!
Snow Water Equivalent
Winter weather can result in snowstorms dumping large amounts of snow in a
short time. The Snow Water Equivalent (SWE) is a common snow pack measurement to
tell the amount of water contained within the snow pack. It is the depth of
water that would result if the entire snow pack melted.
For example, if an empty wading pool filled with 20 inches of new powdery snow
at 15% snow water density and the snow is melted, you would be left with a pool
of water 3.0 inches deep. In this case, the SWE of your snow pack would equal
20" x 0.15 = 3.0 inches.
To determine snow depth from SWE you need to know the density of the snow. The
density of new snow ranges from about 5% when the air temperature is 14° F, to
about 20% when the air temperature is 32° F. After the snow falls its density
increases due to gravitational settling, wind packing, melting and
recrystallization.
The relationship between the snow water equivalent (SWE), snow density, and snow
depth is modeled with the following formula: (SWE) ÷ (snow density) = (snow
depth).
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A recent snowstorm dumped 12 feet of snow in some areas of the northeastern
United States. The falling snow completely filled an empty cylindrical trash can
24 inches tall. Carlos melted the snow in the trash can and found the height of
the water in the can was 3 inches. What was the density of the snow? Express
your answer as a percent.
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What is the Snow Water Equivalent (SWE) in inches of the 12 foot snowfall?
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On February 16, 2007, at the Mt. Hood, Oregon SNOTEL site the SWE was measured
at 37.9 inches and the snow density was estimated to be 40%. What was the
estimated depth of the snow in inches? Express your answer as a decimal to the
nearest tenth.
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To learn more about the techniques used to estimate snow depth and snow water
equivalence visit
http://www.wcc.nrcs.usda.gov/snow/
Answer to last week’s MATHCOUNTS problem:
Two Presidential Dollar coins are made for each Sacagawea Dollar coin. So 2
× 25 = 50 million Presidential Dollar coins divided by 4 different coins is 12.5
million of each Presidential Dollar coin.
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Find the lowest common multiple of 1.75 and 2.00. Factors of 1.75 are 0.25 and 7
and factors of 2.00 are 0.25 and 8. The lowest common multiple of 1.75 and 2.00
has the factors 0.25, 7 and 8. 0.25 × 7 × 8 = 14. Each stack is 14 mm high. 14
÷1.75 = 8 quarters and 14 ÷ 2.00 = 7 dollar coins. The least number of coins she
could have used to make the two stacks is 8 quarters + 7 dollars = 15 coins. 8 ×
0.25 + 7 × 1.00 = 9.00. The total value of the least number of coins she could
have used to make the two stacks is $9.00.
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The density of the Presidential Dollar coin can be expressed as 8.1 ÷ (π ×
13.252 × 2.00). The density of the Quarter can be expressed as 5.67 ÷ (π ×
12.132 × 1.75). Dividing the density of the Dollar coin by the density of the
Quarter gives 1.047.... The ratio of the density of the Dollar coin to the
density of the Quarter is 1.05 when rounded to the nearest hundredth.
If you want to see last week's problem again, click
http://www.mathcounts.org/webarticles/anmviewer.asp?a=980&z=110
Idaho Society of Professional Engineers
PO Box 170239
Boise, ID 83717-0239
208-426-0636
Fax: 208-426-0639
E-Mail: ispe@idahospe.org
Web Site: www.Idahospe.org
Idaho
Society of Professional Engineers
