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Forces and Motion Science Fair Project

Sink or Float?

Sink or Float? | Science Fair Projects | STEM Projects
Ever wonder why some cans of soda sink and others float? Join us in this experiment to find out! We'll measure the mass and volume of each can, and then modify them to make them hover in the middle of a container of water.


The hypothesis is that regular soft drinks are more dense than water, and diet drinks are less dense, leading to the regular soft drink sinking, while the diet soft drink floats.

Method & Materials

You will measure the mass and volume of each can, and then modify them to make them hover in the middle of a container of water.
You will need a balance, an aquarium or other large, deep, straight-sided container filled with water, one sealed can each of regular and diet soda, one empty can of each type of soda, paper towels, pencils and paper for student data tables, ice (optional), plastic foam, finishing nails or metal washers, several sizes, tape, and scissors.


The experiment showed that unopened regular soda cans sink, while unopened diet soda cans float. This is because regular soft drinks are sweetened with dissolved sugar and/or high-fructose corn syrup, which is relatively heavy, while artificial sweeteners in diet drinks are many times sweeter and so they are required in smaller quantities.

Why do this project?

This science project is interesting and unique because it allows students to observe and predict the behavior of regular and diet soft drink cans when immersed in water, calculate the density of solutions using mass-volume data, design and construct a neutrally buoyant vessel, and relate density to neutral buoyancy.

Also Consider

Experiment variations to consider include testing different brands of soda, testing different temperatures of water, and testing different types of plastic foam.

Full project details

You can find additional information and details for this science fair project here. Have fun exploring!

Related video

Hey there! Here are some awesome videos about this science project that we think you'll really like. They're not only super fun, but they'll also help you learn more about the science behind the project. So sit back, relax, and get ready to have some fun!!
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