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Why is concrete so heavy? |
Concrete is a mixture of cement, small rocks and other chemicals that harden when water is added to them. The reason it's so heavy is because it's made of a lot of heavy stuff! It's designed to be heavy! When it hardens, it becomes like a rock itself, strong enough to build tall buildings and bridges that can hold a lot of weight.
Think about the pillow you sleep on. It's pretty light, right? It's also probably very soft and comfy! A chunk of concrete the same size as your pillow could weigh as much as a grown-up person or even more! The difference in weight is because the feathers that make up the pillow are much lighter than the rocks and cement that make up the hard concrete!
Weighing In
Just because two objects are the same size, doesn't mean they're the same weight. If you have a scale at home and a grown-up to watch you, try to find pairs of things around your house that are the same size and weigh them. You might find a cell phone and a small package of tissues, or a phone book and a box of cereal.
Which object weighs more? Can you think of the reasons why? Maybe one has more empty space than another. Maybe one is made of lighter pieces.
Every object has a certain weight for its size. This idea is very important in the world of science. By knowing this information, scientists are able to identify mysterious substances just by weighing and measuring them!