Thread: a phyisic question

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.

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.

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 sweet If you build a bit of expanded foam into the design it can still float even if it does get filled with water.

Cheers

Ian

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.

Why not keep the drums whole and sealed??

Paul

1 ml = 1 cm3 = 1 g

Is that neat or what.

Actually it's neater than that.
1x schoolchild to the power of 1x drum + water = disaster

Originally Posted by Wongo

1 ml = 1 cm3 = 1 g

Is that neat or what.

But only at 4 degC.

That was the original definition of the kilogram. 1L of pure water at 4 degC = 1 kilogram

Look in the boat building forum to get some mathematics that will curl your ears.


Cheers

John
---------------------------

Be Aware. Australia has enough lerts

Originally Posted by masher

But only at 4 degC.

That was the original definition of the kilogram. 1L of pure water at 4 degC = 1 kilogram

Obviously.

Originally Posted by Toolin Around

A google search of Archimedes law of displacement will bring up tonnes on it.

Archimedes said that an imersered object will experience an upthrust equal to the weight of water displaced. that should save you searching

AND OLD WINES CASKS'LL MAKE GOOD FLOATIES

....

Originally Posted by Gingermick

Archimedes said that an imersered object will experience an upthrust equal to the weight of water displaced. that should save you searching

AND OLD WINES CASKS'LL MAKE GOOD FLOATIES

The best bit is emptying them so you can use them...

well that was fun
that was what l was looking for thanks all will tell you how we go in the race