Why does an iceberg float with most of its bulk hidden underwater, while a steel ball sinks steadily through oil at a fixed speed no matter how far it falls? Both questions sit inside this chapter, which NEB and HISSAN exams split into three distinct areas — fluid statics (buoyancy, density, floating bodies), surface tension (capillary rise, angle of contact), and viscosity (Stoke’s law, terminal velocity, Bernoulli’s principle). Each area tends to show up separately in board papers rather than blending together, so it helps to prepare them as three related-but-separate mini-topics.

Numerical problems in this chapter follow recognizable formulas year after year: buoyancy problems almost always involve calculating density from apparent weight loss in a liquid, capillary problems compare rise heights between tubes of different radii, and viscosity problems repeatedly ask what happens to terminal velocity when smaller drops coalesce into one — a pattern worth recognizing early since the same setup reappears across multiple years with different numbers.

The full set of past NEB and HISSAN questions for all three sub-topics is below, sorted by year. Step-by-step numerical solutions for this chapter are available on the Solutions page.