Explore the Buoyancy & Density Lab
Drag objects into fluid and see when they float or sink, with the buoyant force. Free, no signup, runs in your browser.
- Free to use
- No signup
- Nothing to install
- Runs in your browser
Illustration. Open the tool for the real thing.
See it in action
The Buoyancy & Density Lab with sample data entered and the result showing.
What is the Buoyancy & Density Lab?
Drag objects into fluid and see when they float or sink, with the buoyant force. It runs in your browser, so a change to a setting or a drag on an object shows up at once.
Buoyancy explains ships, submarines, hot-air balloons, life jackets and how fish control depth.
3 steps to your result
Open the tool and follow along. Nothing to install.
What you get
Buoyant force equals the weight of the fluid displaced (Archimedes' principle).
An object floats if its density is less than the fluid's.
A floating object displaces water equal to its own weight.
Drop a wood block, then a brick, into water.
Change the fluid to oil, then saltwater, and watch the depth change.
Adjust the object density until it just floats.
Used for
Pick one to see how it fits.
Physics learners
Physics students in middle school, high school and first-year university, teachers who want a quick demonstration for the projector, and anyone revising for exams.
Try it freeTeachers
For teachers: project the Buoyancy & Density Lab on the board, let students predict the result, then run it together and test this: Change the fluid to oil, then saltwater, and watch the depth change. For students: change one thing at a time and write down what changes.
Try it freeHow it compares
A plain look at this tool next to the usual alternative.
| This simulation | Textbook diagram | |
|---|---|---|
| Interactive | Drag, tap and change settings | Fixed picture |
| Install | Nothing to install | Not needed |
| Cost | Free to use | Depends on the book |
Questions people ask
Why do things float?
The fluid pushes up with a force equal to the weight of the fluid the object displaces. If that is at least the object's weight, it floats.
Why does a steel ship float?
Its hull encloses a lot of air, so the ship's average density is less than water. It displaces enough water to support its weight.
Is the Buoyancy & Density Lab free to use?
Yes. The Buoyancy & Density Lab is free, needs no signup or download and runs in your web browser. It is part of the Physics group of AZRS simulations.
Does the Buoyancy & Density Lab work on a phone or tablet?
Yes. The Buoyancy & Density Lab takes touch input as well as mouse input, so you can use its 5 adjustable settings with a finger. A larger screen makes the controls and graphs easier to read.
How do I use the Buoyancy & Density Lab?
1. In the Buoyancy & Density Lab, use the controls to change Liquid, Block material, Mass, Volume, Force arrows. The simulation reacts instantly. 2. In the Buoyancy & Density Lab, pick an option such as Gasoline 700, Water 1000, Honey 1420, Mercury 13600 to switch modes or load an example. 3. In the Buoyancy & Density Lab, press "Lift it out" to start, reset or change what is happening. 4. Start with this experiment: Drop a wood block, then a brick, into water. Drag any glowing handle, object or slider with your mouse or finger and the Buoyancy & Density Lab responds in real time. 5. Change one setting at a time and watch which readout moves, then compare it with this idea: Buoyant force equals the weight of the fluid displaced (Archimedes' principle).
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Try the Buoyancy & Density Lab now
Drag objects into fluid and see when they float or sink, with the buoyant force. Free to use.
Try it free