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Posted by David Sherman on Tuesday, July 14, 2009 at 00:38:05 :
In Reply to: fuel tank capacity posted by Nick on Monday, July 13, 2009 at 23:07:03 :
Here's the lazy modern way to do arithmetic and convert units all at the same time. Say your gas tank is 9" deep by 20" wide by 30" long. Go to google and type:
9 inches * 20 inches * 30 inches in gal
It knows what you're trying to do and gives you the answer:
23.3766234 US gallons
Sometimes you have to play with it a bit to get it to recognize the units correctly, but if you know what's close to being a reasonable answer, you'll know if it's right. Here are a couple of other ways to get the same answer:
9 in * 20 in * 30 in in gal
Note that this time, google was smart enough to figure out that the first three times you typed "in" you meant "inches", but the last time, you meant that you wanted the answer IN gallons.
Another way would be to do the multiplying without units, and then tell it the result was in cubic inches, which you want converted to gallons like this:
(9 * 20 * 30) cu in in gal
If you wanted to be more mathematical about it, you could do:
(9 * 20 * 30) in^3 in gal
the "in^3" part means "inches cubed" or "cubic inches".
In this last forms, you can use "x" instead of "*" to signify multiplying:
(9 x 20 x 30) cu in in gal
In the other versions, you can't. Apparently google gets confused when it sees letters mixed up next to unit indicators. It's safer to always use "*" to mean "times" in the google calculator.
If you wanted your answer in other units, you could type:
9 in x 20 in x 30 in in liters
or
9 in x 20 in x 30 in in cu ft
and it would figure it out correctly.
For a more complicated example, we could figure out the displacement of a hypothetical V8 engine with a bore of 3.9" and a stroke of 3.32" like this:
(pi * (3.9 in / 2)^2) * 3.32 in * 8 in cu in
The stuff in the first parentheses is the "pi R squared" calculation for the area of the top of the piston. This version gives us
"317.283265 cu in" for the answer, but if you want it in liters, just change the "cu in" part to "liters" and you get "5.19934117 liters"
You can even do electrical and mechanical calculations. Here's a simple one. What's the electrical power equivalent to 150 horsepower? Just google:
150 hp in kilowatts
and it tells you:
150 hp = 111.854981 kilowatts
If google doesn't automagically recognize what you're trying to do and give you a "calculator" symbol with the answer, try using a different units abbreviation and make sure you have spaces between all the numbers, symbols, and abbreviations.
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