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Thread: a phyisic question
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9th October 2007, 10:22 AM #1
a phyisic question
is it true that 1 kilo will disperse 1 ltr of water
l have to biuld a boat with school kids going to use 200 ltr drum x 4 cut in half long ways and cut the ends off and make a bow useing pop rievets a plank down the middle + on both sides also we will have a out rig set up
l was going to get them to check thier weight to see if we will stay a float
is there a formular you can use
smile and the world will smile with you
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9th October 2007, 10:42 AM #2
Hi Spirit
1g of water = 1mL therefore 1kg of anything in your boat will displace 1L of water.
A google search of Archimedes law of displacement will bring up tonnes on it.
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9th October 2007, 10:48 AM #3
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water water everywhere
1 litre of water is 1000ccm and it weighs 1 kg.
A floating boat displaces its own weight in water.
The volume of the boat at its lowest section should be measured or calculated (you can actually do this by filling the boat with water and measuring the litres used).
The boat can be weighed on a scale.
If the weight of the boat is less than the volume of water it displaces, it will float.
If the weight is more than the volume of water it dispalces, it will sink.
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9th October 2007, 01:03 PM #4
In the ideal world of physics experiments your boat is going to displace approx 800 litres of water. So if it weighs more than 800kg, it will sink.
Back in the real world you have to have a bit of freeboard before you paddle out into the pond, but it should be fine with an all up weight (raft and passengers ) of 400kgs or so.
Allow a couple more kgs for the lifejackets and it should be sweetIf you build a bit of expanded foam into the design it can still float even if it does get filled with water.
Cheers
Ian
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9th October 2007, 01:27 PM #5
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It will displace slightly less if it's in salt water, but I suppose that's nit picking.
You could also use old car inner tubes for floatation. I once made a catameran raft with a tarp for a sail, and four inner tubes stretched to an oval shape around timbers, for each of the pontoons. I got them for free from a tyre fitting place, but watch out when near barnacles, and bring a paddle for when your rig collapses.
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9th October 2007, 01:34 PM #6
Why not keep the drums whole and sealed??
PaulAll these projects. Not enough lifetimes to finish them.
Paul
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9th October 2007, 01:48 PM #7
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9th October 2007, 01:55 PM #8
'Just hit it harder'
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Actually it's neater than that.
1x schoolchild to the power of 1x drum + water = disaster
.... "Don't tell him your name Pike!"
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9th October 2007, 01:57 PM #9
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9th October 2007, 02:40 PM #10
Look in the boat building forum to get some mathematics that will curl your ears.
Cheers
John
---------------------------
Be Aware. Australia has enough lerts
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9th October 2007, 02:44 PM #11
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9th October 2007, 03:41 PM #12
Last edited by Gingermick; 9th October 2007 at 03:54 PM. Reason: ADDON
Mick
avantguardian
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9th October 2007, 03:47 PM #13
....
- Wood Borer
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9th October 2007, 04:29 PM #14"We must never become callous. When we experience the conflicts ever more deeply we are living in truth. The quiet conscience is an invention of the devil." - Albert Schweizer
My blog. http://theupanddownblog.blogspot.com
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9th October 2007, 07:32 PM #15
well that was fun
that was what l was looking for thanks all will tell you how we go in the racesmile and the world will smile with you
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