Appendix C: Conversion of Units

 

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It often happens that we wish to convert a quantity expressed in one set of units to another set of units.  Fro example, we might want to know how many miles are equivalent to 10 kilometers.  For conversions like this, we make use of conversion factors.  Let us see what a conversion factor is.

 

            We know, for example, that                 

 

            Division by 1.61 km gives                    

                                                or                    

 

This is a conversion factor between miles and kilometers. Note that the conversion factor is equal to one.  When we multiply by a conversion factor, it is the same as multiplying by one.  It does not change the value of the quantity in question.  We shall now give a few examples of the use of conversion factors.

 

1.                     How many miles are there in 10 kilometers?  The appropriate conversion factor is obtained from 1.61 km = 1 mile to be 1 = 0.62 mi/km.  Therefore,

                                   

 

2.                     How many hours are there in 200,000 seconds?  We know that 1 hour - 60 min and 1 min = 60 sec.  Therefore,

                                   

 

Typical conversion factors are given in Appendix B.