I’m sitting in a boat in a pool. In the boat with me is a cannonball. What happens to the level of the pool if I take the cannonball out of the boat and drop it into the pool? Does the level increase, decrease or stay the same?
The level of the water should increase. With the cannonball on the boat and the boat floating, the boat will displace some water. However, when the cannonball is in the water entirely, it cannot rely on the boats floating ability to hold it up, thus the water level will increase.