Work through the list without notes. If you cannot do a statement, follow its link, then come back. Guide = study guide; Practice = practice questions.
Understanding
- I can explain how Newton’s laws apply to a small piece of fluid, and name the forces on it. (Guide: “Newton’s laws inside a fluid”)
- I can state when a fluid’s velocity changes, and explain why equal pressures on both ends mean constant velocity, not rest. (Guide: Worked example 3; Practice Q6)
- I can explain why pressure increases with depth using a force balance on a column of fluid. (Guide: “A fluid at rest”)
- I can explain the buoyant force as the net effect of the fluid’s pressure forces, and why I must not draw both. (Guide: Figure 1)
Skills
- I can derive F_b = ρ_fluid V g from the pressures on the top and bottom of a submerged block. (Guide: “Deriving F_b = ρVg”)
- I can draw free-body diagrams for floating, suspended and tied-down objects. (Guide: Figure 2; Practice Q7)
- I can find a buoyant force, volume and density from two spring-scale readings. (Guide: Worked example 1; Practice Q4)
- I can find how deep a floating object sits, and the extra load that would sink it. (Guide: Worked example 2)
- I can sketch and interpret a graph of scale reading against depth as an object is lowered into a fluid. (Practice Q5)
- I can derive and use a = (P₁ − P₂) / (ρL) for a slug of fluid in a level pipe. (Guide: Worked example 3; Practice Q6)
Reasoning
- I can predict how a submerged fraction, scale reading or acceleration changes when the fluid’s density changes. (Guide: Worked example 2; Practice Q3, Q4)
- I can use Newton’s third law to explain why a balance under a beaker reads more when an object is lowered into the water. (Practice Q2)
- I can justify why the buoyant force on a fully submerged object does not depend on depth or on the object’s material. (Practice Q1, Q7)
- I can decide whether an object floats or sinks by comparing densities, not masses. (Guide: “Floating”; Common misconceptions)
All ticked? Move on to Topic 8.4, Fluids and Conservation Laws, or return to the course roadmap.