Does the water level rise when a boat sinks in a canal lock?

[geoffroy6885]

As the title says, I need major help with a problem for my AP Physics class and I have to explain my answer orally to the class. Here is the question and if you could, could you answer it and follow up with an explanation? Any help would be greatly appreciated. Here it is:

A boat in a canal lock sinks: does the water level rise, sink, or remain the same? Explain!

 

[HallsofIvy]

You posted this on both "k-12 Level Help" and "College Level Help".
Don't you know where you are? (Please do not post the same thing to different forums.)

The response on the "k-12 Level Help" was very good: do an experiment to find out. You can also think about this: the boat sinks because water flows into it and weighs it down. Where does that water come from?

By the way- is this lock completely sealed or being allowed to flow into or out of it?

 

[M98Ranger]

The water level in a canal lock will remain the same. This is because the volume of water displaced by the boat is equal to the volume of the boat itself. When the boat sinks, it will displace the same amount of water as it did when it was floating, thus keeping the water level constant. This is due to the principle of buoyancy, which states that the buoyant force on an object is equal to the weight of the fluid it displaces. In this case, the weight of the boat and the weight of the water it displaces are equal, resulting in no change in the water level. However, if the boat were to sink completely and become submerged, the water level would rise because the volume of the boat is no longer displacing the same volume of water.