Debate: Science-Heads..

[Rekop]

I say it stays the same, a friend says it rises, and a coworker says it lowers. Which is it?!

You’re in a row boat, which is in a large tank filled with water. You have an anchor on board, which you throw overboard (the chain is long enough so the anchor rests completely on the bottom of the tank). Does the water level in the tank rise or fall?

[EimP]

you should do a experiment i can tell you how to set it up >:)

[Z3roN92]

if its heavy enough the water should rise, the only way it lowers if the anchor puts a hole in the bottom lol

[Cameron]

That all depends. The water level may rise due to the new displacement of some water, but this would only raise it slightly. However, the water could also stay at the same level since the weight of the anchor in the boat would have already displaced its weight in water, caused by the boat being lower in the water due to the weight of the anchor (kind of like how when ice cubes melt in a glass of water the water level doesn't rise since the cubes have already displaced their weight in water).

[Derpinator]

The water level should, and most probably will, rise because, to put it simply, you took a body of water and put a solid in it. Because the anchor wasn't previously in it, the water level will rise however it will rise slightly, assuming that it is a decent sized tank, so that you will barely notice it, otherwise everytime a boat set anchor, the ocean levels would rise and flood the coasts :P. But yes, the water level rises.

[Yveltal]

it rises because of water displacement
it lowers because it bears a hole or floods the tank
it stays the same because it fits into the hole or it replaced the lost water

[Derpinator]

Ok guys, I am changing my answer. I thought about that more now that Rekop made me think of it more. :P

The water level will fall because, initially the anchor was in the boat and it was weighing the boat down along with the chain and yourself. So, the whole boat was displacing a lot of water. When you throw the anchor out of the boat, the boat weighs a whole lot less without the chain and the anchor so, while the anchor and chain are out of the boat and in the air, the water level falls relatively a lot. When the anchor enters the water with the chain, it displaces water but not enough water to bring the level back to normal because it has a smaller surface area than the boat it was initially pulling down because it was in the boat so it had to be smaller. So, the water level rises a comparatively small amount so the final water level is lower than the initial level because it first went down and then came up less than it came down, making it a net lowering.

[Rekop]

it rises because of water displacement
it lowers because it bears a hole or floods the tank
it stays the same because it fits into the hole or it replaced the lost water

Well, I think we all know that. The problem is sorting out the matter of whether the boat's submersion with all that added mass would be equal, less, or greater than the mass of the anchor by itself. ;)

[Yveltal]

Well, I think we all know that. The problem is sorting out the matter of whether the boat's submersion with all that added mass would be equal, less, or greater than the mass of the anchor by itself. ;)

then probably stays the same
while the anchor displaces the water, it may overflow the tank and decrease the waterlevel
there are many variables to this question and possibilities
if it were even more specific…

[Derpinator]

then probably stays the same
while the anchor displaces the water, it may overflow the tank and decrease the waterlevel
there are many variables to this question and possibilities
if it were even more specific…

The sizes of the boat and mass could help but we can make a general guess without it probably.