Pressure in Liquids
Pressure in a liquid increases with depth and density because of the weight of liquid above.
▶ Interact
Play with the controls to see the idea in action.
📘 Learn
Pressure in a liquid increases with depth and density because of the weight of liquid above.
- P equals density times g times depth
- Pressure acts equally in all directions
- Dams are thicker at the bottom
🧠 Quick quiz
Three questions. Score 2 or more to complete the topic.
What is Pressure in Liquids?
Within Physics, which covers forces, energy, waves, electricity, magnetism, light and space explained through motion and experiments, this topic explains Pressure in Liquids. Physics topics explain how things move, push, heat up and carry energy, so each one here pairs a definition with a live model you can change.
Check that you can explain Pressure in Liquids in your own words and give one example from everyday life. If you can do that, you have understood the core idea.
Understanding Pressure in Liquids explains how the physical world behaves, from sport and transport to electricity and medicine.
Pressure in Liquids in detail
The pressure in a liquid increases with depth and density: p = ρgh, where ρ is density, g is gravitational field strength and h is depth. It acts equally in all directions at a given depth and does not depend on the shape of the container.
This explains why dams are thicker at the bottom and why divers feel more pressure the deeper they go. Because liquids are almost incompressible, pressure applied at one point is transmitted throughout, which is the principle of hydraulic systems used in car brakes, lifts and diggers to multiply force.
How the interactive helps you understand Pressure in Liquids
Watch the gas particle model in the interactive. Use any sliders or buttons it offers to change the values and see how the gas particle model responds.
Before you change anything, predict the result. Then change one value at a time and check whether your prediction was right. This is a quick way to build a correct mental model of Pressure in Liquids.
Real-life uses and examples
- Answer “explain” questions by linking Pressure in Liquids to a clear cause and effect.
- Predict what a ball, car or circuit will do with Pressure in Liquids before you do the calculation.
- Explain everyday devices, such as brakes, lifts or chargers, using Pressure in Liquids.
Common mistakes to avoid
- Forgetting that some quantities, such as force or velocity, also have a direction.
- Mixing up Pressure in Liquids with a related quantity that has different units.
- Learning the definition without testing it. Use the quiz and the interactive to check that you can apply the idea.
Frequently asked questions about Pressure in Liquids
What is Pressure in Liquids?
Pressure in a liquid increases with depth and density because of the weight of liquid above.
What are the most important points about Pressure in Liquids?
The main points are: P equals density times g times depth; Pressure acts equally in all directions; Dams are thicker at the bottom.
Why is Pressure in Liquids useful?
Understanding Pressure in Liquids explains how the physical world behaves, from sport and transport to electricity and medicine.
How can I practise Pressure in Liquids?
Open the interactive at the top of this page and change the controls one at a time. Predict the result before each change, then take the three-question quiz. A score of two or more marks the topic as complete on this device.
Which topics are related to Pressure in Liquids?
Related topics in Physics include Work Done, Conservation of Energy, Energy Resources.