Liquids at Rest: Density and Upthrust: JAMB Physics Questions, Answers & Notes

What Liquids at Rest: Density and Upthrust covers in the JAMB Physics syllabus

Density = mass/volume (kg/m³); relative density = density of a substance ÷ density of water (no unit; water is 1000 kg/m³). Archimedes' principle: the upthrust (buoyant force) on a body in a fluid equals the weight of fluid it displaces — this also equals the body's apparent loss in weight. A body floats when its weight equals the upthrust (the law of flotation: a floating body displaces its own weight of fluid); it sinks when denser than the fluid and stays suspended when their densities match. A steel ship floats because its shape displaces enough water. A hydrometer measures a liquid's relative density.

For Liquids at Rest: Density and Upthrust, JAMB expects you to be able to:

• Distinguish density and relative density and calculate them
• State and apply Archimedes' principle and the law of flotation
• Explain sinking, floating and the use of the hydrometer

Key facts & revision notes: Liquids at Rest: Density and Upthrust

These are the recurring points our Liquids at Rest: Density and Upthrust questions test — revise them until each feels automatic, then practise the questions above to lock them in.

• Density = mass ÷ volume, with SI unit kg/m³.
• Density's SI unit is kilogram per cubic metre, kg/m³.
• Density = mass/volume = 600/200 = 3 g/cm³.
• Relative density (specific gravity) = density of substance ÷ density of water.
• Relative density is a ratio of two densities, so it has no unit.
• Upthrust (buoyant force) = weight of the fluid displaced by the body.
• A floating object is in equilibrium: its weight equals the upthrust on it.
• Law of flotation: a floating body displaces a weight of fluid equal to its own weight.
• Upthrust = weight in air − apparent weight in water = 50 − 40 = 10 N.
• A hydrometer measures the relative density (specific gravity) of a liquid.
• A body sinks when its density is greater than the fluid's density.
• Ice is less dense than liquid water, so it floats.
• Water has a density of about 1000 kg/m³ (or 1 g/cm³).
• Upthrust = weight of displaced water = 50 cm³ × 1 g/cm³ = 50 gf.
• Density = relative density × density of water = 0.8 × 1000 = 800 kg/m³.
• The hull's shape displaces a large volume of water, so the upthrust equals the ship's weight.
• When immiscible liquids settle, the denser one sinks to the bottom.
• The apparent loss in weight equals the upthrust (weight of fluid displaced).
• In a less dense liquid there is less upthrust, so the hydrometer floats lower (sinks deeper).
• When densities are equal, weight equals upthrust everywhere, so the body stays suspended.
• Density = mass/volume = 800/400 = 2 g/cm³.
• Relative density 2 means twice the density of water.
• Mass displaced = 0.2 kg, weight = 0.2 × 10 = 2 N.
• By the law of flotation, it displaces its own weight of fluid.

Worked examples

Three Liquids at Rest: Density and Upthrust questions with the answer and a short explanation, so you can see how the topic is set before you practise the full set.

How Liquids at Rest: Density and Upthrust is tested in JAMB Physics

Our Liquids at Rest: Density and Upthrust bank holds 40 questions (11 easy, 21 medium, 8 hard). JAMB Physics typically returns to Liquids at Rest: Density and Upthrust year after year, so steady practice on this topic is high-value revision. Questions are multiple-choice with four options, and at UTME pace you get roughly 40 seconds each — which is why timed practice matters.

How to answer Liquids at Rest: Density and Upthrust questions

Work the stem first and predict the answer before you look at the options; then eliminate the ones that contradict the key facts above. Watch for “which is not…”, “all of the above” and “except” style stems, which are where rushed candidates lose easy marks on Liquids at Rest: Density and Upthrust. If a calculation or a precise definition is involved, work it from first principles rather than guessing from a half-remembered rule. When two options look right, re-read the stem for the qualifier that separates them — JAMB rarely repeats an option by accident. If you are still unsure, eliminate the two weakest choices to lift your odds, flag the question, and move on; never burn a full minute on one Physics item when the exam gives you about forty seconds each. Then come back to flagged questions with whatever time remains. The single most reliable way to get faster at Liquids at Rest: Density and Upthrust is repeated timed practice, so use the button above until the recurring patterns feel automatic.

Common mistakes to avoid in Liquids at Rest: Density and Upthrust

The errors that cost marks on Liquids at Rest: Density and Upthrust are usually careless rather than conceptual: misreading a negative stem, confusing two similar terms, or rushing a definition you actually know. Candidates also over-rely on “expo” and last-minute cramming instead of understanding the topic — which fails the moment JAMB rephrases a familiar idea. Treat every option as a claim to be checked against the facts above, keep your working tidy for any calculation, and don’t change a considered answer on a hunch. Above all, revise Liquids at Rest: Density and Upthrust actively by answering questions, not just by re-reading notes — recall under time is what the exam rewards.

Frequently asked questions

Is Liquids at Rest: Density and Upthrust part of the JAMB Physics syllabus?

Yes. Liquids at Rest: Density and Upthrust is a recognised topic in the JAMB Physics syllabus, covering distinguish density and relative density and calculate them. You should be able to recall its key facts and apply them to multiple-choice questions.

How many Liquids at Rest: Density and Upthrust questions can I practise on Belmadeng?

There are 40 original, JAMB-standard Liquids at Rest: Density and Upthrust questions in our free bank, each with the correct answer and a worked explanation. You can practise them untimed or as a timed test.

What are the most important points to know about Liquids at Rest: Density and Upthrust?

Density = mass/volume (kg/m³); relative density = density of a substance ÷ density of water (no unit; water is 1000 kg/m³). Archimedes' principle: the upthrust (buoyant force) on a body in a fluid equals the weight of fluid it displaces — this also equals the body's apparent loss in weight. A body f…

How do I answer Liquids at Rest: Density and Upthrust questions quickly in JAMB?

Read the stem carefully, eliminate clearly wrong options, and match the remaining choices to the key facts for Liquids at Rest: Density and Upthrust. Practising timed Liquids at Rest: Density and Upthrust questions builds the speed you need for UTME's pace of about 40 seconds per question.

Are these JAMB Physics Liquids at Rest: Density and Upthrust questions past questions or original?

They are original questions written to JAMB (UTME) standard and mapped to the official syllabus — not reproduced past papers. This keeps them legal to use freely while closely mirroring how the real exam tests the topic.

Where can I practise Liquids at Rest: Density and Upthrust questions free without signing up?

Right here — tap “Start Liquids at Rest: Density and Upthrust practice” on this page to begin instantly. Belmadeng's CBT practice is completely free and needs no sign-up, download or subscription.

About these questions: original, JAMB-standard items written from the official UTME Physics syllabus (last reviewed 2026-09-18). Belmadeng is an independent study platform and is not affiliated with JAMB. Spotted an error? Use the report link.