This higher tier covers Higher Tier: Pressure in Fluids and Upthrust within Density for GCSE Physics. Revise Density in Particle Model for GCSE Physics with 13 exam-style questions and 30 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 10 of 13 in this topic. This section is most useful once the core foundation idea is secure, because it adds the detail that pushes answers higher.
Topic position
Section 10 of 13
Practice
13 questions
Recall
30 flashcards
🎓 Higher Tier: Pressure in Fluids and Upthrust
Pressure in a fluid increases with depth according to: P = ρ × g × h
- P = pressure (Pa)
- ρ = density of the fluid (kg/m³)
- g = gravitational field strength (10 N/kg)
- h = depth below surface (m)
Upthrust arises because pressure is greater at the bottom of a submerged object than at the top. This pressure difference creates a net upward force.
Archimedes' Principle: The upthrust on an object equals the weight of fluid it displaces. If upthrust ≥ weight of object, the object floats.
This explains why a steel ship floats — its hollow shape displaces a large volume of water, so upthrust equals its weight even though steel itself is much denser than water.