Weight of water

A conversation among Whalers
jimh
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Weight of water

Postby jimh » Fri Apr 03, 2020 9:30 am

GIven that 1-cm3 of water weighs 1-gram:

How much does 1-foot3 of water weigh?

ANSWER = 62.43-lbs

Derivation:
(1-gram/1-cm3) × (2.54-cm/1-inch)3 × (12-inch/1-foot)3 × (1-kg/103gram) × (2.2046-lbs/1-kg) = 62.427-lbs/feet3

fno
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Joined: Thu Oct 15, 2015 10:01 pm

Re: Weight of water

Postby fno » Fri Apr 03, 2020 10:10 am

Fresh water or salt water, Jimh? Actually it's fresh. Saltwater averages 64.1 lbs/cubic foot. That is why many Boston Whalers sit higher in salt water than fresh. Imagine the waterline of a Boston Whaler sitting in the Dead Sea which averages 77.4 lbs/ cubic foot.

Aside: These facts are some of the important information that is eventually drilled into scuba divers heads after they spend countless $$ on furthering their diving education.

Tacky79
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Re: Weight of water

Postby Tacky79 » Fri Apr 03, 2020 10:14 am

A couple of conversions that I somehow remember, but come in handy:

1 ft3 = 7.48 gallons
120,000 gallons of water = 1,000,000 lbs of water
128 ounces in a gallon
454 grams in one pound

I taught my kids how to do unit conversions using the train track or monorail method, and it's really handy to know this, as you really don't need formulas anymore.

https://www.katmarsoftware.com/articles/railroad-track-unit-conversion.htm
2017 Boston Whaler Montauk 190 w/ 150 Merc/Fish Pkg/Bowrail delete/aft seating
1979 Boston Whaler Harpoon 5.2 sailboat with sails and a tiller :D

jimh
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Location: Michigan, Lower Peninsula
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Re: Weight of water

Postby jimh » Fri Apr 03, 2020 10:33 am

You have to like the metric system:

If 1-cubic-cm of water weighs 1-gram, then 1-cubic-meter weighs 1,000,000-grams or 1,000-kg.

1-gram/1-cm3 × (102-cm/1-meter)3 × (1-kg/103-gram) = 103-kg/1-meter3

jimh
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Re: Weight of water

Postby jimh » Fri Apr 03, 2020 10:46 am

How I learned how many pounds in a kilogram:

My doctor had an old fashioned beam balance scale to measure a patient's weight, the type where you stand on the scale and slide weights across a calibrated beam to find the balance point. The calibrated scale had a pivot at each end, so it could be inverted. One side of the beam read in pounds, the side other read in kilograms. I think the doctor liked to record the patient weight in kilograms in his charts.

On one visit, it so happened that when I stepped on the scale, I weighed 220-lbs. The nurse flipped over the calibrated beam to reveal the weight in kilograms--100 exactly. I felt a little lighter at 100-kg than I did at 220-lbs. Before that visit, I would have needed to look up the conversion. But ever since then, I've known the conversion factor in my head.

Jefecinco
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Re: Weight of water

Postby Jefecinco » Sat Apr 04, 2020 10:26 am

Assignment as the Operations Officer to the Public Works Department in a NATO Headquarters in Europe required a fast brain change. First to convert metric to US for a week or so then to think in metric. It's a great system.
Butch