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  = 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

************************************************

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

12 miles x  = 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 don’t 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.