Fun on Friday: Why is My Ice Floating on My Water?

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Fun on Friday

Why is my ice floating on my water?


It’s a hot summer day. You’ve been playing outside and now you are thirsty. You get a glass, put in some ice and pour yourself a nice glass of water. You set the glass on the counter and reach into the cupboard above it to get a snack. A rock you collected earlier falls out of your pocket and plops into the glass of water.

What do you notice?

The rock sinks to the bottom and the ice does what? It floats! WHAT?!!

As a Discovery Detective, you develop a question.

Why does my ice, which is a solid, float and my rock, which is also a solid, sink?

 Because of DENSITY .

Density is a term used by scientists to describe how much matter a substance has in a certain volume(the space an object takes up).

Suppose you have an ice cube and a rock that are exactly the same dimensions and take up the same amount of space.

Now suppose you have X-ray eyes and can see the molecules inside the 2 objects.

Here is what you see.

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There is more substance in the rock of the same size as the ice cube.

So the rock is MORE DENSE than the ice cube.

But, why does it sink in your glass of water?

Here is an X-ray view of the molecules inside the liquid water.

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The water density, or amount of substance in a certain space, is in between the ice density and the rock density.

Objects that are less dense than the liquid they are in will float.

Objects that are more dense (denser) than the liquid they are in will sink.

So, the ice floats and the rock sinks.

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OK, I hear you. What? Ice and water are the same substance.

So, if ICE FLOATS on WATER, what does that tell you about the DENSITY of ICE (SOLID WATER) compared to the density of LIQUID WATER?


How can that be?

Join me next week on Fun on Friday when we find out the answer.

In the meantime, do some research of your own, Discovery Detective! Learn about water and its different states of matter, density, sinking and floating. See if you can explain this by next Friday.

Have a great weekend!


Nature Mamaw


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