Unit Conversions
From here on in chemistry you will want to know how to do unit conversions. Unit conversions are a way of changing units on a substance, but still keeping the substance equal to the same amount. Unit conversions are done in almost every field of math and science.
Let's say I have two pies and each pie has 7 slices. How many slices do I have? Not that hard right? Well that is what a unit conversion is. What if I asked you how many slices are in 20 pies? Mathematically you would solve this by the following method:
From the information give above we have been told that 7 slices are in a pie. Would you agree with the statement that 7 slices = 1 pie? Sure! If they equal one another, doesn't 7 slices/1 pie = 1? They are the same quantity, just different units. One is in slices, and the other is an entire pie. This is what we call a unit conversion. We arrange a unit conversion so the units cancel. We want the pies to cancel and the slices to remain in the above equation. Therefore we arranged the equation so the pies in the numerator of the first term cancel the pies in the denominator of the second term and just leaves slices.
| Problem 1.1 |
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| Problem: Convert 5,778 seconds to minutes
Plan: We know that 60 seconds = 1 minute. Therefore, we can set up a unit conversion to solve for the minutes. Answer:
Discussion: The units cancel the way we want them to, and we are left with minutes since the seconds cancel out. |
| Problem 1.2 |
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| Problem: Convert 250 miles/hour to kilometers/minute, given the fact that 1 mile equals 1.609 kilometers.
Plan: We will use a unit conversion to convert the miles to kilometers and the hours to minutes. Answer: |
problem 1.1 & 1.2
mohamud aseir
13 Dec 11 at 8:28 am