Under Pressure: Fluid Pressure & Depth
Drag a pressure gauge into a tank and see how depth, density and gravity change pressure.
Drag the pressure gauge into the water. Pressure grows with depth. Fill or drain the tank, change the liquid and gravity, and switch the tank shape. At the same depth the pressure is the same in every shape.
About the Under Pressure: Fluid Pressure & Depth
Free under pressure: fluid pressure & depth. Drag a pressure gauge into a tank and see how depth, density and gravity change pressure. Drag, change the sliders and see the result live. No sign-up, works on phone and computer. Built for physics, the under pressure: fluid pressure & depth runs instantly in your browser: change a setting or drag an object and the result updates at once, so you learn by trying things out rather than only reading about them.
Drag a pressure gauge into a tank and see how depth, density and gravity change pressure. Use it to explore physics ideas at your own pace, then check what you found against the key ideas further down this page.
How to use the Under Pressure: Fluid Pressure & Depth
- Use the controls to change Liquid, Gravity, Air above, Tank shape, Faucet (fill), and more. The simulation reacts instantly.
- Pick an option such as Gasoline 700, Water 1000, Honey 1420, Mercury 13600 to switch modes or load an example.
- Where you see a glowing handle, object, weight or atom, drag it with your mouse or finger. Everything responds in real time.
- Watch the readouts and graphs update as you experiment, and compare what you see with the key ideas below.
Things to try
- Drag the gauge to 3 m depth in water.
- Switch to mercury.
- Turn off the atmosphere and see the gauge fall.
Key ideas you can learn
- P = P₀ + ρ g h.
- Pressure increases with depth.
- Pressure depends on density and gravity but not on the shape of the container.
- Atmosphere adds 101 kPa on top.
Where this is used in the real world
Divers, submarines, dams and water towers are designed using fluid pressure.
Who is this simulation for?
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. It works well for flipped classrooms because students can explore before the lesson.
For teachers: project it on the board, let students predict what will happen, then run it together. For students: change one thing at a time and write down what changes.
Frequently asked questions
Why does pressure increase with depth?
The liquid above pushes down, so more depth means more weight above.
Does the shape of the tank matter?
No. At the same depth the pressure is the same, whatever the shape.
Is the Under Pressure: Fluid Pressure & Depth free to use?
Yes. It is completely free, with no signup, no download and no ads inside the simulation. It runs in your web browser.
Does the Under Pressure: Fluid Pressure & Depth work on a phone or tablet?
Yes. It uses touch as well as the mouse, so you can drag objects with your finger. A larger screen makes the controls easier to see.