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By Ruth Barnard


What is Density?

Density is the amount of mass something has per unit of volume. A denser object will be heavier than a less dense object even if they are the same size, because it essentially has more packed into it – it's more dense. 

For example a block of concrete is heavier than a block of polystyrene of the same size. This is because the block of concrete has a higher density, it has more mass in the same volume which is due to the atomic structure of the object.


Experiment with Density

Density isn't restricted to objects, liquids have a density too and this experiment uses three liquids of varying densities. In the experiment you will make predictions about the density of liquids and objects and put it to the test!


What you need:

 • 2/3 cup or 150ml Syrup ( get the cheapest you can, taste doesn't matter for experiments)

• 2/3 cup or 150ml Vegetable Oil

• 2/3 cup or 150ml Water

• Small objects of varying densities (eg: penny, small ball of paper, lego piece or raisin)

• Clear glass or jar

• Paper and pencils 

• Food colouring (optional)

Note: You could also just use just 1/3 which is often not much more than 1 cup in size and will also cost less. We wanted this much so it would look even more impressive for photos. It's up to you.


Prepare the Liquids:

• These three liquids have different densities. Can you try and guess what order they would go in from least dense to most dense?

• Pour your water into the jar or glass followed by the oil and then syrup

• Watch as each layer settles. Was your prediction right?

TIP: you can add a drop of food colouring to your water to help you distinguish between the layers better. 



Predict, Test and Conclude:

1. Collect together at least five different objects that you think may have varying densities. Like a coin, a small toy, small piece of paper, paper clip, piece of lego, a raison or a nut

2. Write down your predictions about where each object will sit in the jar

3. One by one put the objects in the jar and write down your observations about how they sink or float

4. Write your conclusions by listing your objects from least to most dense, remembering the most dense will be the heaviest and will sink to the bottom

5. Try the experiment again with new objects or liquids...


Extras for experts

Add salt or sugar to your water, does this make it more or less dense?


Let us know your findings and conclusions

Happy Experimenting!


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