Another physics question - aquaducts!

[aldi]

Short but sweet: When a barge is travelling along an aquaduct, does any extra weight come to bear on the supports? Or is it just displacing water, giving no net gain?

[wedg1e]

Well, even the displaced water has to go somewhere, so some of the force it exerts pushing other water out of the way will be transferred into a vertical load

From E=MC2 we can see that Einstein was barking...

Oh I don't bloody know, ask me something else

[2 sMoKiN bArReLs]

..depends is the fridge is full

[Platinum]

www.skeptics.com.au/quiz/0406.htm

Does that answer the question?

[rich 36]

displacement surely,
or how else would that barge lifting wheel thingy work

[edtvr]

how long is the canal?

[tvrbob]

The barge will displace an equal mass of water so theoretically there will be no extra mass. The reality is that the displaced water will need to flow away, therefore that extra mass will be there at first but will dissipate over time. If the barge is motionless then it would not add to the mass of the water, if it is in motion then it would alter the mass because it has a raised water level ahead of it, a lowered water level behind and the displaced water mass is in the process of dissipating. Overall the mass would be higher but less than the sum of both water and barge.

[havoc]

Yes.

Although water is displaced, the water displaced moves ahead-of and behind the barge. Therefore as it moves along the canal/aqueduct, there is a 'length' of water that is slightly higher than the original water level, therefore heavier.


But, except for maybe near-centre of the aqueduct, the additional load won't be as great as the mass of the barge.

[2 sMoKiN bArReLs]

What about if there's a (shut) lock at each end?

[hugoagogo]

the weight of the barge is spread over the whole length of the enclosed waterway

[Pigeon]

hugoagogo said:

the weight of the barge is spread over the whole length of the enclosed waterway

Beat me to it

[2 sMoKiN bArReLs]

Pigeon said:

hugoagogo said: the weight of the barge is spread over the whole length of the enclosed waterway Beat me to it

..and therefore the weight is greater, by the weight of the barge

[aldi]

rich 36 said:

displacement surely, or how else would that barge lifting wheel thingy work

Barge lifting wheel thingy???

So the general consesus seems to be 'no' or 'a little bit'... its kind of bizzare to imagine a big boat ontop of the thing and no extra force, it doesnt seem intuative at all. Whichcraft I say!

[hugoagogo]

2 sMoKiN bArReLs said:

Pigeon said: hugoagogo said: the weight of the barge is spread over the whole length of the enclosed waterway Beat me to it ..and therefore the weight is greater, by the weight of the barge

no, it increase the pressure, (psi, for example) on every square (underwater) inch of the waterway equally, so some of it goes in sideways force and some goes either end of the viaduct (up to where the next lock is) ((and i suppose some forces lengthways against the locks themselves))

>> Edited by hugoagogo on Sunday 29th January 21:50

[lord summerisle]

untill the water level rises above the bypasses, and the exess water flows away...

[hugoagogo]

lord summerisle said:

untill the water level rises above the bypasses, and the exess water flows away...

yeah, plus this ^

[SuPaSpArK]

Archimedes Law of Buoyancy- Buoyancy is equal to the amount of weight displaced!
Therefor: A neutral point is achieved as the barge sits in the water and no extra weight is applied to the structure.
As the barge moved the lateral forces would nominal.
Supes.

[2 sMoKiN bArReLs]

SuPaSpArK said:

Glyn's Law of Bollox- Buoyancy is equal to the amount of weight displaced! Therefor: A neutral point is achieved as the barge sits in the water and no extra weight is applied to the structure. As the barge moved the lateral forces would nominal. Supes.

[SuPaSpArK]

Your going down brother like that in barge......

[hugoagogo]

SuPaSpArK said:

Archimedes Law of Buoyancy- Buoyancy is equal to the amount of weight displaced! Therefor: A neutral point is achieved as the barge sits in the water and no extra weight is applied to the structure.

pish, even assuming all the water was at sea level connected to the oceans, it would increase the load on all the whole ocean's floors by an infitesimal amount

how much water the boat displaces is irrelevant