You Melted My Ice

A full glass of water with a single ice cube sits on a table. When the ice has completely melted, will the level of the water have increased, decreased or remain unchanged?

The water level remains unchanged because the ice cube displaces its own weight. If you’re not convinced, read Archimedes’ Principle, which states that any floating object displaces its own weight of fluid. Still not convinced? Here are a few more sources.

Posted in Brain Teasers


6 Comments on "You Melted My Ice"

Hamail hussain says
May 8, 2015 @ 04:00

The weight of the ice is supported by the buoyant force of the water in which it is floating. If you drop an ice cube into a glass of water, it will raise the level of the water. By how much? By an amount that exactly equals the weight of the ice cube. Then, when the ice cube melts, it will turn into an amount of water. How much? Exactly the weight of original ice cube.

The water level goes up when you drop the ice cube into the glass. After that, it does not change when the ice cube melts

JB says
August 6, 2015 @ 13:27

The answer given is only true if the ice cube was floating in the water at the start of the experiment. If the glass has only a little water and the cube is resting on the bottom then the water level will go up when it has melted.

The Sphinx says
December 18, 2015 @ 20:33

Doesn’t the ice cube have air? At the start, I immediately thought, “The same”, but I thought it might decrease a little because the ice cube has air in it.

Kouwpee says
December 14, 2016 @ 07:27

It needs a bit of chemistry knowledge to solve. Ice’s density is less than water, so the water level will go down

Adam says
December 14, 2016 @ 23:20

Per what Kouwpee stated. The Archimedes principle only applies with bodies of constant volume. The water of the ice cube will actually expand and increase the volume of water in the glass.

Here is an easy experiment to show this in reverse…. Cut open the top of a coke can. Fill halfway with water. Mark the water level with a permanent marker. Freeze! Observe how the volume in the can has magically changed!!!

Adam says
December 14, 2016 @ 23:23

Need to edit my comment… meant to say the volume of water will decrease in the glass. Water is denser than ice.

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