"Natural Science 4" is an interactive encyclopedia that includes scientific information in the understanding of fourth grade students, wonderfully illustrated and animated.
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* Chapter 4 Lesson 20 *
* FLOATING BODIES *
Have you ever wondered why, when placed on water, some bodies sink and others float? Think of the pebbles that you throw with such pleasure, making them "hop" on the water and "draw" as many circles as possible on its surface. It sinks in eventually, doesn't it? But what if you use a ping pong ball instead of pebbles? It will float unhindered.
The explanation lies in the density of the bodies. Those with a lower density than water will float, and those with a higher density will sink.
Practically all the bodies around us: solid, liquid or gas are made up of small particles. The more "crowded" they are, and the distances between them are very small, the higher the density of that body.
A coin, potato, or metal ball will sink because they have a high density, while a bottle, rubber ducky, or stick will float because the density of the materials they are made of is low.
But why does ice float? Why don't these mountains of ice, called icebergs, sink? Ice appears as a solid body with a higher density than water. Let's put it under the microscope to find out. What a surprise! Frozen water has more trapped air. 1 liter of water increases its volume by almost 10% by freezing. So, I concluded! Ice floats because it is less dense than liquid water.
Now let's think about a paper boat! Placed on water, it will float. The same thing happens with a real steamer.
How does an object with such a large mass manage to float while a stone, however small, sinks rapidly?
To understand better, you need to know about Archimedes principle. This scholar of the ancient world discovered that any body immersed in a liquid is pushed up from below with a force equal to the weight of the volume of liquid it displaces, that is, pushes it aside.
The steamer has a long and wide base. The greater the amount of water it displaces, the greater the force with which it is pushed upwards. If this force is equal to or greater than the weight of the vessel, it will float.
Make a list of 5 objects that float and 5 objects that sink.