AP Physics 1 / Topic
Fluids
Unit 8 covers fluids at rest and in motion: density and pressure, hydrostatic pressure with depth, Pascal's principle, buoyancy and Archimedes' principle, the continuity equation, and Bernoulli's equation.
What the exam asks
- Compute absolute and gauge pressure at depth in a fluid
- Apply Pascal's principle to hydraulic lifts
- Use Archimedes' principle for floating and submerged objects and apparent weight
- Apply the continuity equation to flow through changing pipe cross-sections
- Use Bernoulli's equation (and Torricelli's theorem) to relate pressure, speed, and height
Key formulas and rules
ρ = m/V; P = F/A
P = P0 + ρgh (depends on depth, not container shape)
F(b) = ρ(fluid)·V(displaced)·g; floating: F(b) = weight
A1v1 = A2v2 — narrower pipe, faster flow
P + ½ρv² + ρgh = constant; faster flow ⇒ lower pressure
efflux speed v = √(2gh)
Question bank breakdown
43
3
11 easy · 26 medium · 6 hard
Skills covered
Every question in the bank comes with a per-choice explanation, so you learn why each wrong answer is wrong — not just the key.
Practice this topic
The full set of Fluids questions — with a per-choice explanation on every answer — lives in the practice workspace. Start free, no account needed.
Study tip
The buoyant force uses the fluid's density and the displaced volume — never the object's density. A floating object displaces its weight in fluid; a sunken one displaces its volume.