Does the water level in a container increase if you have rocks in a boat floating on the water moved into ...?

Question

Will the water level in a container of water increase, decrease, or stay the same if you intitially have a couple of rocks in a boat floating on the water then have the rocks moved into the container of water?

Answer 1

Assuming the rocks do not float, the water level will go down.  

The reason is, when the rocks are in the boat, they displace exactly their weight in water.   When they are moved out of the boat and into the water, they sink and because of that, they are unable to displace as much water as they did when their weight was in the boat.    

Answer 2

First, let's see if I the scenario right.  You have a toy boat floating in a bucket of water.  You have some rocks in the toy boat.  You have clearly marked the water level on the side of the bucket.  

If you take rocks from the boat and drop them into the water, the water level will go down.  

When the rocks are in the boat the boat sits low in the water.  It displaces a volume of water that weighs the same as the boat and rocks. Water's density is 1 so the volume of water displaced is high.  

When the rocks are submerged in the water they displace only the amount of water equal to their volume.  Assuming these are not some kind of trick rocks or pumice, but just your garden-variety stones, their density is greater than 1.  That means their volume is less than the volume of water that is the same weight.  

So the amount of water displaced in less, the water level in the bucket will go down.  

Answer 3

Depends on the size of the rocks relative to the boat's size. If you have small but heavy rocks, then level should go down.