Everything that we've covered in this course so far has been applied to solid objects (specifically rigid objects that do not deform or change shape).

But many of the physical laws, concepts and equations that we've learned also apply to fluids.

A fluid is a material that has no fixed shape and will continue deforming if any force is applied to it. The category of fluids includes liquids (like water) and gasses (like the atmosphereic air around us) and we're going to learn about both. The main difference between the two is that liquids are (nearly) incompressible and do not change volume when compressed, but gasses are very compressible. In this lesson we'll learn about ideal fluids which are incompressible and have no viscosity (they flow more like water than honey).

We're going to learn about density, which is how much mass a fluid has per unit of volume. This is what determines whether an object will sink or float in water (or any fluid). Density is a simple concept but we're going to use it a lot in the next few lessons.

Multiple-Choice Questions

Answers

Free-Response Questions

Fluids (previously in AP Physics 2)

Note: These are questions from AP Physics 2 exams before 2025. For some questions only parts of the question are relevant to the Fluids unit in AP Physics 1 as noted below.

• 2023 Q3 - - Tank of water with pipe and two blocks, fluids, forces, buoyant force, flow, Bernoulli's equation, continuity equation
• 2022 Q1 - - (Part a) Block in tank of water hanging from string, fluids, forces, FBDs, buoyant force
• 2021 Q2 - - (Parts b and c) Balloon held underwater, fluids, density, pressure, forces, buoyant force
• 2018 Q4 - - (Parts a and c) Boat carrying steel bars, fluids, forces, buoyant force, flow, continuity equation
• 2017 Q1 - - Water flowing through pipe, fluids, flow, continuity equation, Bernoulli's equation, conservation of energy, forces, FBDs, buoyant force

• Characteristics of a Fluid
• States of Matter
• What Is Density?
• Density

• Organic Chemistry Tutor - Density Problems
• Density Practice Problems
• Advanced Density Problem
• Density problem examples

• TED-Ed - Why does ice float in water?
• Efficient Engineer - Understanding Fluids and Viscosity
• Hyperphysics - Fluids

• Volume conversion tool

Everything that we've covered in this course so far has been applied to solid objects (specifically rigid objects that do not deform or change shape).

But many of the physical laws, concepts and equations that we've learned also apply to fluids.

A fluid is a material that has no fixed shape and will continue deforming if any force is applied to it. The category of fluids includes liquids (like water) and gasses (like the atmosphereic air around us) and we're going to learn about both. The main difference between the two is that liquids are (nearly) incompressible and do not change volume when compressed, but gasses are very compressible. In this lesson we'll learn about ideal fluids which are incompressible and have no viscosity (they flow more like water than honey).

We're going to learn about density, which is how much mass a fluid has per unit of volume. This is what determines whether an object will sink or float in water (or any fluid). Density is a simple concept but we're going to use it a lot in the next few lessons.

Multiple-Choice Questions