The purpose of this workshop and homework assignment is for you to become comfortable converting between different units of measurement, a skill necessary to all forensic scientists. Many publications in the United States still use the English system, whereas many scientists use the metric system. Therefore, it is often necessary to convert between the two systems. Feel free to work in groups on this assignment, but each student should turn in a copy. SHOW YOUR WORK!!!!
Length
1) It is useful to be able to estimate lengths in the metric system. Examine a ruler, and get an idea of the length of a millimeter, centimeter, and meter.
|Common Units of Length |Abbreviation |Meter Equivalent |
|Millimeter |mm |1000 mm = 1 m |
|Centimeter |cm |100 cm = 1 m |
|Decimeter |dm |10 dm = 1 m |
|Meter |m |1 m |
|Kilometer |km |1 km = 1000 m |
a) An adult's height may be about 1) 1.7 km 2) 1.7 mm 3) 1.7 cm 4) 1.7 m
b) The longer edge of a credit card is about 1) 8.5 mm 2) 8.5 cm 3) 1.7 cm 4) 1.7 m
c) The thickness of the wire in a paper clip is about 1) 1 mm 2) 10 mm 3) 1 cm 4) 10 cm
d) The width of this sheet of paper is about 1) 22 m 2) 22 dm 3) 22 cm 4) 22 ml
It is very useful to know how to convert between units in the metric system.
Example problems:
1) Convert 34.5 mm to m.
[pic]
2) Convert 23.6 mm to km. (HINT: You can avoid careless mistakes by first converting from mm into m, and then converting from m to km.)
[pic]
2) Convert 345 cm into m
3) Convert 12.5 cm into mm
4) Convert 829 cm into km
5) Convert 42.5 km into cm
6) A rectangular piece of fabric with a length of 1.20 meters and a width of 0.85 meters must be divided into twelve, equal sized units for forensic sampling purposes. What are the dimensions of the twelve smaller portions?
Volume
Volume is a measure of how much space an object takes up.
|Common Metric Units of Volume |Abbreviation |Meter Equivalent |
|Liter |l |1 l |
|Milliliter |ml |1000 ml = 1 l |
7) Take a look at the relative sizes of liters and milliliters and circle the appropriate volume.
a) One aluminum can of soda is about 1) 3.5 ml 2) 35 ml 3) 350 ml 4) 3.5 l
b) A small glass of orange juice is approximately 1) 2.0 l 2) 2.0 ml 3) 200 ml 4) 20 l
c) A gallon of milk is about equal to 1) 380 ml 2) 3.8 ml 3) .38 ml 4) 3.8 l
The following unit conversions may be helpful:
1 in = 2.54 cm 1 m = 3.3 ft
1 ft = 12 in 1 yard = 36 inches
1 cm3 = 1 mL 1 metric ton = 1000 kg.
1 in3 = 16.4 cm3 2.2 lb. = 1 kg
1 ft3 = 28.3 liter 28.4 g = 1 oz.
1 gal = 3.79 liter 16 oz. = 1 pound
4 qt = 1 gallon 1 acre = 43560 ft2
8) Which of the above is a unit of length? Which of the above is a unit of mass?
Which of the above is a unit of area? Which of the above is a unit of volume?
Converting between the English and Metric systems is very similar to problems you did above.
Example problems:
1) Convert 346.5 lb. to kg.
[pic]
2) Convert 23.6 cm to ft.
[pic]
9) Convert 32.3 cm to inches.
10) Convert 465 liters to cubic feet.
11) A murder victim weighs 150 pounds. How much does he weigh in grams?
12) You are given 3 yards of tape to make evidence labels. How many labels 20 cm in length can you make?
Practice with Scientific Notation and Powers of Ten
13) Convert the following numbers into scientific notation.
a) 100
b) 10,000
c) 10,000,000
d) 0.001
e) 0.000001
f) 0.1
g) 1
14) Arrange the following numbers, written as powers of 10, from the smallest to the largest: 100, 10-14, 102, 10-3, 10-7, 104, 10-9, 105 , -10
15) Convert the following to scientific notation:
a) 4,256
b) 6,234,000
c) 0.0026
d) 0.00005689
e) 24,5000
f) 0.00000000012
g) 3.405
h) 7,000,000,000
Write the following numbers in standard notation.
16) 6.5 x 10–5
17) 3.22 x 109
18) 8.314 x103
19) 4.08 x 10-12
20) Identify the type of notation, standard or scientific, that would make the most sense for each situation below. Explain.
a) The length of a football field measured in inches…
b) The mass of an apple in pounds…
c) The mass of an ocean liner in pounds…
d) The length of a fingerprint in centimeters…
e) The diameter of a hair shaft in centimeters…
f) The amount of blood found pooled beside a victim’s head in gallons…
g) The number of fibers found as trace evidence under the victims fingernails.
Practice Unit Conversion Problems
21) 104 mm into cm
22) 962 cm into km
23) Convert 54 mL to cubic centimeters.
24) Calculate the number of seconds in 3.6 years.
25) Measure your height in inches; then convert it to centimeters.
26) A tire impression left in the mud at a crime scene was 8.7 inches wide. Convert this to centimeters.
27) A murder suspect was found 200 miles from the crime scene 150 minutes after the time of death. Assuming he actually committed the murder, how fast (in miles per hour) would he have had to drive in his getaway car? Given this information, is he a realistic suspect?
28) How many 325 mg tablets can be produced from 2.50 kg of ibuprofen?
29) A crime suspect fled the scene when police officers entered the building. The police are planning to set up a search, but need to know a realistic search radius. How far could he run in 10 minutes if he can run 5 miles per hour?
30) One baked potato provides an average of 31.0 mg of vitamin C. If 5.0 lb. of potatoes has 15 potatoes, how many milligrams of vitamin C are provided per pound of potatoes?
31) Forensic scientists must be careful to avoid communicable diseases such as HIV/AIDS. In body fluids such as blood or saliva, the HIV virus can survive over 15 days at room temperature and longer if refrigerated. How many hours can the HIV virus survive in liquid at room temperature?
32) The tread on a suspect’s car tire is worn to 1/16th of an inch. Convert this to millimeters.
