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What is Density? |
Our Planet
Density might seem like a difficult scientific concept, but it really just tells us how much stuff takes up a certain amount of space.
Maybe you have a backpack for school. Imagine that backpack just holds one pencil. It would be pretty light. Right? And there would be plenty of room to add more things if you needed to.
Now imagine the same backpack, but this time it’s filled with 100 pencils, 500 crayons, 20 notebooks, and every book you can squeeze in there. That backpack that used to be pretty light has just gotten a lot heavier, and there just isn’t much room to add anything else! We could say that the backpack is very dense. When it just had one pencil inside, it wasn’t very dense at all!
Knowing about density helps a lot of people! Shipbuilders use it to make sure their boats float. Scientists can use it to help figure out what a mysterious object is. Postal workers can use it to help figure out shipping costs.
Now that you have a basic idea of what density is, I should stop writing this article before it gets too dense!
Notes on what floats!
Have you ever had a rubber duck in a bathtub with you? It floats on the water while you sit on the bottom of the tub. Why is that? The rubber duck is made out of a light plastic and it has air inside. The overall density of the duck is less than the water it sits on. It floats!
When dealing with liquids, like the water in your bathtub, an object that is less dense than the liquid will float on top of it!
If you dropped a penny into a cup of water, what would happen? Ask a grown-up to help you find items that you can safely put in water. Then, ask your grown-up to help you fill a large bowl with water. What happens when you put the items you found in the water? Do they float or do they sink? Are these items more or less dense than the water?