CONVERTING UNITS

 Many students are intimated when they have to convert units in a problem. However if you use a systematic approach this is not hard. Here is the approach I suggest. First, some basic rules:

 1) Always carry the units along in your problems, this way the units do not get separated from the numbers. Use a clean sheet of paper to work a problem and work down from the top to the bottom in an organized way.

 2) Always set up the problem on paper first before trying to use a calculator to get an answer.

 To convert units, we use a Conversion factor which has a value equal to 1. So, for example, to convert three dozen eggs into the actual number of eggs

  3 dozen eggs x [1] = 3 dozen eggs

 3 dozen eggs x [C.F.] = 3 dozen eggs; so long as C.F. = 1

 3 dozen eggs x [12 eggs/1 dozen eggs] = 36 eggs; since 12 eggs = 1 dozen

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Try converting miles to kilometers. You need to know that 1.6 km = 1 mile

 12 miles x [1] = 12 miles

 12 miles x [C.F.] = 12 miles; so long as C.F. = 1

 12 miles x [1.6 km/mile] = 19 km;

 since 1.6 km = 1 mile; the C.F. [1.6 km/mile] = 1

 Sometimes, it is easiest to use two conversion factors when you donít know the conversion factor to use in one step.

Try these problems:

Convert--

a)14. 4 feet into inches

b)15 years into days

c) 4.5 x 103 metric tons (mt) into kilograms

d) 4.5 x 103 metric tons (mt) into pounds (lbs)

e) 1.65 x 105 days into years

f) 4.7 x 102 metric tons (mt) into kilograms

g) 6.5 tg into kilograms

1 inch = 2.54 centimeter (cm)

1 mile = 5280 feet

1 year = 365 days

1 metric ton = 1000 kilograms (kg)

1 kilograms (kg) = 2.2 pounds

1 kilogram (kg) = 103 grams

1 teragram (tg) = 1012 grams

 I strongly recommend that you do these problems first before looking at the answers below.

 Answers:

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Initial Value

x CF#1

x CF#2 (if needed)

Final Value

a

14.4 feet

12 inches

foot

-

172.8 inches

or 1.73 x 102 inches

b

15 years

365 days

year

-

5475 days

or 5.48 days

c

4.5 x 103 mt

103 kg

mt

-

4.5 x 106 kg

d

4.5 x 103 mt

103 kg

mt

2.2 lbs/kg

9.9 x 106 lbs

e

1.65 x 105 days

1 year

365 days

-

452 years

or 4.52 x 102 years

f

4.7 x 102 mt

1000 kg

1 mt

4.7 x 105 kg

g

6.5 tg

1012grams

tg

1 kg

1000 grams

6.5 x 109 kg