Help!! metric units
- Thread starter lillybeth
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\(\displaystyle 2550\text{ m}\cdot\dfrac{1\text{ km}}{1000\text{ m}}=2.55\text{ km}\)
You see, we multiply the distance by \(\displaystyle 1=\dfrac{1\text{ km}}{1000\text{ m}}\) for two reasons:
i) we don't change the value
ii) we cancel the unwanted unit and leave the wanted unit.
Does this make sense?
You see, we multiply the distance by \(\displaystyle 1=\dfrac{1\text{ km}}{1000\text{ m}}\) for two reasons:
i) we don't change the value
ii) we cancel the unwanted unit and leave the wanted unit.
Does this make sense?
Lillybeth
The metric system is one of the great simplifications because it takes advantage of decimal notation, just like US money. If you can convert dollars to cents or cents to dollars, you can understand the metric system. Before the US became independent, it used the traditional European monetary divisions, 4 farthings in a penny, 12 pennies in a shilling, and 20 shillings in a pound. So 2111 farthings = 2 pounds, 3 shillings, 11 pennies, 3 farthings. Horrible. And we still use the traditional units of length and mass. A mile = 8 furlongs, 1 furlong = 40 rods, 1 rod = 5.5 yards, and 1 yard = 1 foot. So the number of feet in a mile = 3 * 5.5 * 40 * 8 = 16.5 * 320 = 5280.
Unit of length is the meter.
Multiples of the meter or fractions of the meter are preceded with prefixs from Latin (for fractions) or ancient Greek (for multiple).
The most common prefixs are centi, meaning 0.01 units, milli, meaning 0.001 units, and kilo, meaning 1000 units.
Converting between units just involves shifting a decimal point. 2550 meters = 2.550 kilometers. Or 2.550 meters = 255.0 centimeters.
Easy as pie.
MarkFL has shown you what is I believe to be the best way to convert units. It is frequently called dimensional analysis, but it basically rests on the notion that multiplying by one changes nothing important. Of course, once you get used to metric units, you can do many conversions in your head by sliding decimal points around.
The metric system is one of the great simplifications because it takes advantage of decimal notation, just like US money. If you can convert dollars to cents or cents to dollars, you can understand the metric system. Before the US became independent, it used the traditional European monetary divisions, 4 farthings in a penny, 12 pennies in a shilling, and 20 shillings in a pound. So 2111 farthings = 2 pounds, 3 shillings, 11 pennies, 3 farthings. Horrible. And we still use the traditional units of length and mass. A mile = 8 furlongs, 1 furlong = 40 rods, 1 rod = 5.5 yards, and 1 yard = 1 foot. So the number of feet in a mile = 3 * 5.5 * 40 * 8 = 16.5 * 320 = 5280.
Unit of length is the meter.
Multiples of the meter or fractions of the meter are preceded with prefixs from Latin (for fractions) or ancient Greek (for multiple).
The most common prefixs are centi, meaning 0.01 units, milli, meaning 0.001 units, and kilo, meaning 1000 units.
Converting between units just involves shifting a decimal point. 2550 meters = 2.550 kilometers. Or 2.550 meters = 255.0 centimeters.
Easy as pie.
MarkFL has shown you what is I believe to be the best way to convert units. It is frequently called dimensional analysis, but it basically rests on the notion that multiplying by one changes nothing important. Of course, once you get used to metric units, you can do many conversions in your head by sliding decimal points around.
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Yes, as JeffM mentioned, when converting from one metric (or Scientific International) unit to another, all you need do is move the decimal point. No need to recall obscure equivalencies.
However, I wanted to show you the method I was taught by my dad as a child, and later saw was very useful in physics. For example, suppose you wish to convert feet per second to kilometers per hour, you could write:
\(\displaystyle \displaystyle x\frac{\text{ft}}{\text{s}}\cdot\frac{12\text{ in}}{1\text{ ft}}\cdot\frac{127\text{ cm}}{50\text{ in}}\cdot\frac{1\text{ km}}{100000\text{ cm}}\cdot\frac{3600\text{ s}}{1\text{ hr}}=\frac{3429x}{3125}\,\frac{\text{km}}{\text{hr}}\)
I did not mean to imply that I disagree with MarkFL on the importance of dimensional analysis. It is a life saver in chemistry and physics and undoubtedly other disciplines that I never studied.
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I interpreted your reply as that you were agreeing that dimensional analysis is a good technique to use in general. :cool:
I just wanted to explain to the OP why I gave the method, rather than the more direct route in her case of being able to just move the decimal point.
I just wanted to explain to the OP why I gave the method, rather than the more direct route in her case of being able to just move the decimal point.
Ok one of the easiest ways I have found to do this is to "move decimal places" according to how many 0's you have.
In this case, 2,550 Meters is 2,550. <-- See the decimal?
Then you know 1,000 meters is in 1 Kilometer.
So you have three 0's in 1000 so move your decimal three places in.
This allows you to conclude 2.550 is your answer!
I hope this gave you an easier way to look at it!
In this case, 2,550 Meters is 2,550. <-- See the decimal?
Then you know 1,000 meters is in 1 Kilometer.
So you have three 0's in 1000 so move your decimal three places in.
This allows you to conclude 2.550 is your answer!
I hope this gave you an easier way to look at it!
lillybeth
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Yes it did help alot. Thankyou!Ok one of the easiest ways I have found to do this is to "move decimal places" according to how many 0's you have.
In this case, 2,550 Meters is 2,550. <-- See the decimal?
Then you know 1,000 meters is in 1 Kilometer.
So you have three 0's in 1000 so move your decimal three places in.
This allows you to conclude 2.550 is your answer!
I hope this gave you an easier way to look at it!