German Water Bridge

[crokett]

Lessay the water in that acqueduct weighs 50,000 metric tons. Now if a barge weighing 1,000 metric tons is added to it, the total weight now carried by the acqueduct is 51,000 metric tons. So the canal better be designed to carry the added weight of all the vessels in it's water.

Or somebody tell me if it's way past my bedtime and i shd head to bed .

You are correct. If I fill a 5 gal bucket halfway with water it will weigh ~20lbs. If I drop a 15lb weight in the bucket I'd expect it now to weigh 35 since it won't displace enough water to slop over the sides.

Taken further, if I fill the bucket to the brim and then drop the weight in, I still expect it to be heavier. the weight is denser than the water, so it sinks. AFIK displacement is a statement of volume, not weight so the weight won't displace 15lbs of water, it will displace only as much as it needs to find room in the bucket. OTH, if I take a big rubber ball and push it down to the bottom of the bucket, the bucket will weigh less than when I started because the water displaced by the ball weighs a lot more than the ball does.

[Richard in Smithville]

Hmmm...I know and have no arguments with that statement, but in this specific situation, there's more to it. 'Displaces' is not a right term here, as I am sure the water in that canal stays there, despite addition of new vessels (ie, it does not overflow out of it).

Lessay the water in that acqueduct weighs 50,000 metric tons. Now if a barge weighing 1,000 metric tons is added to it, the total weight now carried by the acqueduct is 51,000 metric tons. So the canal better be designed to carry the added weight of all the vessels in it's water.

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That would work if it were a completely closed system, but the water bridge is connected to canals on each end so the displaced water has somewhere to go without going over the sides. There is a view on google maps