Water Bridge
Check out this bridge.
It took 6 years and 500 million euros to build! At 918 meters long, this is the largest water bridge. It was built over the Elbe River in Magdeburg, Germany.
I found a neat trivia question about the bridge: Did that bridge have to be designed to withstand the additional weight of ship and barge traffic, or just the weight of the water?
Answer:
It only needs to be designed to withstand the weight of the water! Why? A ship always displaces an amount of water that weighs the same as the ship, regardless of how heavily a ship may be loaded. Neat, huh?
It took 6 years and 500 million euros to build! At 918 meters long, this is the largest water bridge. It was built over the Elbe River in Magdeburg, Germany.
I found a neat trivia question about the bridge: Did that bridge have to be designed to withstand the additional weight of ship and barge traffic, or just the weight of the water?
Answer:
It only needs to be designed to withstand the weight of the water! Why? A ship always displaces an amount of water that weighs the same as the ship, regardless of how heavily a ship may be loaded. Neat, huh?
posted by CJ at 3/20/2007 07:02:00 AM
6 Comments:
Yes the more a ship weigth the more the level of the wather increase, the presence of the ship become an increment of water, but if it become too much it pour out from the bridge
"It only needs to be designed to withstand the weight of the water! Why? A ship always displaces an amount of water that weighs the same as the ship, regardless of how heavily a ship may be loaded. Neat, huh?"
It would be neat if it were true, but it's false. It is true that a floating object displaces an amount of water equal to the object's weight (Archimedes' Principle), but the weight of the water and boat together is higher that the weight of the water alone. This is true regardless of whether the object floats on the surface or lies on the bottom. The increase in total weight added by the boat is generally very small compared to the weight of the water. The increase in total weight is significant only if the object causes the water level to rise appreciably. In an extreme case, if the floating boat caused the water level to rise to twice its initial height, the weight of the boat and the weight of the water are equal.
Question: A water glass is partially full with water and several floating ice cubes. When the ice melts, does the water level go up, stay the same, or go down?
"It only needs to be designed to withstand the weight of the water! Why? A ship always displaces an amount of water that weighs the same as the ship, regardless of how heavily a ship may be loaded. Neat, huh?"
This statement is true, assuming that when the boat displaces the water, the displaced water flows off the bridge.
"Question: A water glass is partially full with water and several floating ice cubes. When the ice melts, does the water level go up, stay the same, or go down?"
The water level will rise slightly.
I'll buy the comments above, however jpf should be only slightly corrected in that there would be structural considerations as to if the load is imposed as displacement at the surface of the water or a point load applied at the bottom of the water. Not when factoring the design of the columns, but only the allowable span and strength of the concrete base which directly supports the distributed and point loads - unless of course the point load is not centric to the column locations.
The water level will go down as the ice melts. Water is unusual in that in its solid form (ice) it is actually less dense than in its liquid form. This is why ice floats on water. So, when it melts it turns into its more dense form, water, and since water is denser, it takes up less volume.
"The water level will go down as the ice melts. Water is unusual in that in its solid form (ice) it is actually less dense than in its liquid form. This is why ice floats on water. So, when it melts it turns into its more dense form, water, and since water is denser, it takes up less volume."
Somehow I dont think you are joking. Please think again.
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