Bunch of dudes tried making a Bronze age boat, but it sinks
35 replies, posted
Yeah it's pretty bad journalism to not say whether if it sprung a bunch of leaks or if half the boat sank and took a lot of water
[QUOTE=Overv;35964387]To calculate the volume and thickness of the boat to keep a certain amount of people afloat.
Gravity exercises a downwards pointing force on the boat and the people inside and buoyancy counteracts that force. The trick is to make sure that force is large enough by calculating the volume of the boat that will be underwater:
[img]http://puu.sh/uQvE[/img]
[img]http://puu.sh/uQqY[/img]
Where Fg is the force of gravity and Fb is the buoyancy force. The gravity is directly proportional to the total mass of the boat (m[sub]b[/sub]) and the people inside (m[sub]p[/sub]), g here is Earth's gravitational constant averaging 9.81 m/s[sup]2[/sup].
The buoyancy force is proportional to the volume of the water occupied by the boat (V[sub]d[/sub]), the density of the water (p[sub]w[/sub]) and the gravitational constant.
These forces need to cancel each other out so that the boat has no vertical movement, which means the following equation needs to be solved for the displaced volume:
[img]http://puu.sh/uQss[/img]
The gravitational constant g cancels out:
[img]http://puu.sh/uQsF[/img]
(That means that your boat will behave the same on other planets!)
Finally solving for the displaced volume:
[img]http://puu.sh/uQt1[/img]
That means that if you have a boat that weighs 50 kg (regardless of material) and two persons weighing 140 kg together:
[img]http://puu.sh/uQtG[/img]
A volume of 0.19 cubic meters will be displaced. If you assume your boat is about 150 cm long and 50 cm wide, your boat will need to be at least 25 cm high for water to not leak in and sink your boat (1.50*0.50x0.25~=0.19).[/QUOTE]
Dude, little correction - g ( gravitational force) is equal to 9.8 m/s^2
I just checked it at 10th grade physics book.
Though it wont make a huge difference anyways.
Everything else is right though.
[QUOTE=overpain;35980564]Dude, little correction - g ( gravitational force) is equal to 9.8 m/s^2
I just checked it at 10th grade physics book.
Though it wont make a huge difference anyways.
Everything else is right though.[/QUOTE]
I was going by standard gravity rounded to 3 significant digits:
[url]http://en.wikipedia.org/wiki/Standard_gravity[/url]
[QUOTE=overpain;35980564]Dude, little correction - g ( gravitational force) is equal to 9.8 m/s^2
I just checked it at 10th grade physics book.
Though it wont make a huge difference anyways.
Everything else is right though.[/QUOTE]
uh pretty sure his is just one decimal place more accurate
[editline]16th May 2012[/editline]
and when i say "pretty sure" im being condescending. it is
[editline]16th May 2012[/editline]
but it seems im late so it doesnt matter anyway
at least they tried
Yeah i'm going to side with craftsmanship error instead of mathematical.
They were working for months on it, and in that time it's near impossible for such a collective of people working together to completely blank out on the most important aspects of the boat and why is floats.
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