Physics · Lesson Worlds
Buoyancy: interactive science lab
Change how dense the object is and prove that it floats only when the water is denser.
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What will you learn?
An object floats when it is less dense than the fluid. Denser than the water, it sinks.
How does the lab work?
Observe the simulation, make a prediction, change a variable, run the experiment, and explain the result. Finish with a challenge that tests your understanding.
You can change: Density. Compare what happens and connect the result to the scientific explanation.
Try a comparison in Buoyancy
Start with the lab’s initial settings. Choose one control below, predict the result, and change that control while keeping the others fixed. Record the setting and what you observe before making a second change.
- Density: the lab starts at 0.85 g/cm³; its available range is 0.4–1.4 g/cm³.
For a named starting condition, try Cork, Wood, Stone. A preset can change several settings: check the controls before treating two presets as a one-variable comparison.
Questions to discuss during the activity
- Watch what happens. The water pushes up. The block’s weight pushes down. Watch the block sit in the water.
- Name the cause. Buoyancy is the upward push of the fluid. If the block is less dense than the water, that push wins and it floats. If it is denser, it sinks. Density decides float or sink.
- Change something. Lower density toward cork and it should sit higher. Change density, then drop it in.
- Guess before you run. If we set density to 1.25 g/cm³, the block will… Guess what will happen, then run to check.
After your comparison, explain how the observations connect to this idea: An object floats when it is less dense than the fluid. Denser than the water, it sinks. Name one condition you held fixed and one feature of the real world this model simplifies. A completed run is a starting point for discussion, rather than proof of mastery.
Who is it for?
Curious learners exploring physics. A parent or teacher can help younger learners read the instructions and discuss the results. Choose by topic and prior knowledge rather than a fixed grade level.
Is this lab free?
Yes. This interactive lab is free without signing in or a paid membership.
No app download is needed; interactive play requires JavaScript and a modern browser.
Use this activity with a learner
Families and educators · choose by prior knowledge
Learning goal: An object floats when it is less dense than the fluid. Denser than the water, it sinks.
Before you begin: Read the controls for Density. Make one prediction before changing a setting.
Check understanding: Ask for one observation, the evidence that supports it, and a question to investigate next.
A simulation simplifies the real world. Explain which conditions stayed fixed; a successful run alone does not demonstrate mastery.
Explore why objects float or sink: prediction, evidence, and follow-upShare Buoyancy with your family or class. No account is needed to open the free resource.
Activity and guide by Lesson Worlds. About the platform.
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