Thursday, 25 October 2007 - 5:48 PM EDT

The water level would go down because there is less displacemennt. With the metal in the boat it had the density to displace a certain amount of water. With the metal remove the boat displaces less and the displacement of the metal (because it is very dense and dosn't have much volume) isn't enough to make up for the difference.

Thursday, 25 October 2007 - 10:03 PM EDT

I agree with Giovanna. I think the overall water will go down because the volume of the ship is so much larger than the volume of the iron. Though there will be the same amount of weight pushing on the water, the iron blocks are so much more dense because their volume is much more compact. The boat will also float higher in the water so that negative change in displacement is less than the added displacement of the iron directly in the water.       

Thursday, 25 October 2007 - 11:00 PM EDT

I think that the water level would remain the same.  Since the displacement is based on density, Mass/volume, nothing is changing.  The boat is still taking up the same amount of space as it was before and the iron blocks aren't being removed from the water they're just being moved from the boat.  so the amount of mass in the water is the same.

Since Giovana and Mary Beth said the same thing I'd have to disagree with both because there's no change in anything in the system.

Thursday, 25 October 2007 - 11:39 PM EDT

I agree with Matt I think that the water level would stay the same. It is like the problem we did in class when you leave a glass of water with an ice cube in it when the ice melts the water level stays the same. It is the same idea here the boat when full with the scrap iron it will displace a certain amount of water. Then once you empty out the boat since it has less massive it will displace less water, which will cause the water level to go down in the pool. However, when you place the scrap iron back in the pool the scrap iron will displace the difference so, it will keep the water level will remain the same. Since the mass that is in the pool is the same through out the water level should remain the same. 

Thursday, 25 October 2007 - 11:51 PM EDT

I'm with Chris and Matt on this one.  Since the iron was in a ship already, the water for the mass of the iron was already displaced, so when the iron is dumped into the water from the boat, the iron is now taking up more volume directly and the boat is taking up less volume since its total mass is decreasing.

Friday, 26 October 2007 - 5:54 AM EDT

I agree with Giovana and Mary beth on this one. The boat displaces a lot more water than the iron does, and the iron when in the boat displaces an amount of water equal in weight to the iron, because the boat still floats. When the iron is thrown overboard, the iron sinks because it doesn't displace enough water outisde the boat, thus the water level sinks.

Friday, 26 October 2007 - 7:19 AM EDT

I think that the water level will decrease since one of the principles of fluids says that an object immersed n fluid will displace a volume of fluied equal to the volume immersed.  If the iron was already in boat it gave the boat a bigger displacement since density is equal to the mass/volume so the water has to displace as much water as the weight of the ship.  Therefore when the iron is thrown overboard the ships weight will decrease hence the iron has been removed and the water displaces less water because of the weight that the boat lost consequently causing the water to decrease.  The iron will take up space in the water so it will also act to raise the water level since it is taking up space in the water but it will not affect the water from lowering or raising that much because of it's smaller surface area.  So, I agree with Bob on this answer answer because he agrees as well that that the water will decrease. 

Saturday, 27 October 2007 - 11:21 AM EDT

Hey,

The answer to this question is that the water level will sink slightly.  For each piece of iron in the boat, the boat has to displace a volume of water that has a weight equal to weight of the piece of iron.  Since iron is denser than water, the boat has to displace a volume of water greater than the volume of the iron so that the weights are equal.  When the iron is taken out of the boat, the water level goes down because the boat is no longer diplacing that volume of water.  Then, when the iron scrap is placed in the pool, the water level goes up because the iron is displacing a certain volume of water.  However, the water level does not return to the original height because the iron scrap is not displacing a volume of water that has a weight equal to its own.  The iron sinks because the weight of the volume of water it displaced does not equal its own.  This means that less water is displaced by the iron than by the boat because the boat floated and the iron did not. 

Saturday, 27 October 2007 - 11:30 AM EDT

I would like to respond to Matt Hazzard's post. 

Matt said that the amount of mass in the water would not change, so therefore the water level would not change.  However, you have to think of this system in terms of density.  When the iron is in the boat, the boat creates a large container of a defined volume.  Thus you could calculate the average density by dividing the total mass by the volume created by the ship's hull.  When a scrap of iron is removed, the average density of the ship goes down, so it floats higher and displaces less water, so the water level goes down.  When the iron is placed back into the water, its density has changed.  It is no longer part of the average density of the ship, but instead has its own density which is much greater than water.  Previously, the iron had been floating as part of the ship system, but now it has sunk, meaning that there had to have been a change in the amount of water displaced.  The iron does not displace enough water to equal its mass, so ultimately, less water is being displaced than before, meaning that the water level has gone down slightly.