gwalys
starting to spend too much on rocks
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Member since December 2006
Posts: 126
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Post by gwalys on Mar 16, 2007 20:41:28 GMT -5
You are in a boat in a swiming pool. In the boat you have a 12" diameter cannon ball made of lead. You take the cannon ball out of the boat and gently lower it over the side and allow it to sink to the bottom.
The question I pose to you is this:
Will the water level in the pool go up, go down, or stay the same?
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Post by Cher on Mar 16, 2007 20:46:22 GMT -5
Stay the same ...
Just to clarify ... it wasn't me in the boat. I don't have one and I don't have a swimming pool either.
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Post by cookie3rocks on Mar 16, 2007 21:45:09 GMT -5
Stay the same. Before you put the cannon ball in the boat, the level was lower. Right?
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Post by beefjello on Mar 16, 2007 21:56:57 GMT -5
My guess is the water level lowers.
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Post by Cher on Mar 16, 2007 22:13:36 GMT -5
My thought is this ... When you take the cannon ball out of the boat, the boat will rise, lowering the water level. When you put the cannon ball into the water, it will raise the water back to the same level it was when the cannon ball was in the boat.
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Post by parfive on Mar 16, 2007 23:17:18 GMT -5
Cher: "Just to clarify ... it wasn't me in the boat. I don't have one and I don't have a swimming pool either." Therefor you DO have a 12" cannonball . . . . . ooops, wrong riddle. ![:)](//storage.proboards.com/forum/images/smiley/smiley.png) Rich
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Post by parfive on Mar 16, 2007 23:21:26 GMT -5
I'll say the water level stays the same. The ball either displaces water by being weight in the boat, or by being in the pool.
Rich
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stoneman92
starting to shine!
Member since February 2007
Posts: 30
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Post by stoneman92 on Mar 16, 2007 23:36:57 GMT -5
When the cannon ball is in the boat it displaces its own weight of water. When it is thrown into the pool it displaces its own volume in water. As the ball is more dense than water it displaces more water due to its weight than due to its volume.
The water level falls.....
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Post by Cher on Mar 17, 2007 0:21:12 GMT -5
;D Hey Rich ... ![](http://www.rosebudm.com/bp/neener.gif)
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gwalys
starting to spend too much on rocks
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Member since December 2006
Posts: 126
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Post by gwalys on Mar 17, 2007 7:08:30 GMT -5
Perfect answer stoneman While in the boat the cannon ball will displace about 44-45 gallons of water. The cannoin ball in the pool will displace about 4 gallons of water. A simple experiment I have my students do is to take a paint can cap or similair cap and put it in a measuing cup with about a cup of water in it. In the cap they put a 2 oz fishing sinker and note the water level. They then take the sinker out of the cap and place it at the bottom of the measuing cup and note the water level. The water level goes down.....
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