Water Bridge over a River!

[Canuck]

Check this out...

Even after you see it, it is still hard to believe!
Water Bridge in Germany . What a feat!
Six years, 500 million euros, 918 meters long.......now this is engineering!
This is a channel-bridge over the River Elbe and joins the former East and West Germany ,
as part of the unification project. It is located in the city of Magdeburg , near Berlin .
The photo was taken on the day of inauguration.
To those who appreciate engineering projects, here's a puzzle for you armchair engineers
and physicists.
Did that bridge have to be designed to withstand the additional weight of ship and barge traffic,
or just the weight of the water?

[rolly_wood]

As physicist, who, it is known, try always to oversimplify problems by neglecting something  , I would say that the weight of the boats could be neglected with respect to that of water. But this is a question for engineers and I am not 

[Canuck]

Very interesting answer Rolly...let's wait to hear from some of our 'resident engineers' 

[Roby]

It is just the weight of the water that needs to be addressed, the weight of the boat will perfectly dispalce the same weight of water.

This, however, is not the case with say, "a truck load of flying pidgeons".  In that case, even though the birds are in flight in the truck's cargo hold, you still have to account for thier weight because of the force applied to the cargo hold floor by the flapping if thier wings.  

The only difference between the two scenerios is that with the boats, the force of its weight is displaced.  With the birds, that force has no were to go.

AMMENDMENT:  If the bridge is part of a lock system, then you would have to compensate for the weight because you would have to put more water in to get different sized boats to remain boyant.   Also, if a boat happened to sink in the middle of the bridge, its weight would then be a factor.

[rolly_wood]

Touchè Roby! I thought to a closed system but it is a shame that at a first sight I honesty did not account for my connational Archimede. Good point John!

[Jack]

But I do hope they accounted for the weight of the spectators...

[Canuck]

But I do hope they accounted for the weight of the spectators...

Yeah, I was thinking of that also...

[rolly_wood]

But I do hope they accounted for the weight of the spectators...

Otherwise that's enough they dive 

[rolly_wood]

John this quiz risks to cause a marriage crisis. I told this matter to my wife who is an engineer, I have ever used to sympathetically criticize for her"schematic reasoning", and she replied instantaneously as Roby. When I said that I replied that way she started to pull my leg, and I am afraid it will last long time...

thanks by her 

 

[RKB]

No exit lanes? Poor design!

[Canuck]

No exit lanes? Poor design!

That's funny Ry 

[Roby]

Now how about this:  Will a cannon with a cannonball put down its barrel recoil backwards (kick) more than a cannon with no cannonball.  Both cannons have the same amount of explosive charge used.

Or how about this :  Does a boat weigh more or less depending on if the moon is direclty overhead?

 

[rolly_wood]

John this quiz risks to cause a marriage crisis.

  not having proper control of language: ........... kidding of course!  

EDIT  Wait Roby: I need to ask 

[rolly_wood]

Or how about this :  Does a boat weigh more or less depending on if the moon is direclty overhead?

I am gambling my 'reputation' now: Weight is a force which depends on mass (which does not change) and gravity acceleration which is roughly constant on the earth's surface, but moon could be a small perturbation then I would say it would weight a bit less in terms of force (Newton) the same in terms of mass (Kg).
Of course if the boat travels much slower than light otherwise mass does change. 

[Canuck]

Now how about this:  Will a cannon with a cannonball put down its barrel recoil backwards (kick) more than a cannon with no cannonball.  Both cannons have the same amount of explosive charge used.

Or how about this :  Does a boat weigh more or less depending on if the moon is direclty overhead?

 

Your questions made me think of this:

What do you call a 'Newfie' (otherwise known as a Canadian 'Redneck') in a tree?


A Branch Manager!