Ratio & ProportionTopic Summary

Knowledge Organiser: Density

Part of Density · GCSE GCSE Mathematics revision

This topic summary covers Knowledge Organiser: Density within Density for GCSE Mathematics. Revise Density in Ratio & Proportion for GCSE Mathematics with 14 exam-style questions and 3 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 6 of 6 in this topic. Use this topic summary to connect the idea to the wider topic before moving on to questions and flashcards.

Topic position

Section 6 of 6

Practice

14 questions

Recall

3 flashcards

Knowledge Organiser: Density

Key Terms

Density: The mass packed into a unit volume of a substance
Mass: The amount of matter in an object (measured in g or kg)
Volume: The amount of space an object occupies (measured in cm³ or m³)
Units (density): g/cm³ or kg/m³
Floating: An object floats if its density is less than 1 g/cm³ (less dense than water)

Must-Know Facts

Density = Mass ÷ Volume
Mass = Density × Volume
Volume = Mass ÷ Density
Water has density 1 g/cm³ — objects with density < 1 float
1 g/cm³ = 1000 kg/m³
Always include units in your answer

Key Formulas

D = M ÷ V
M = D × V
V = M ÷ D
Use the DMV triangle: cover the unknown to find the formula

Common Mistakes

Unit mismatch: Density in g/cm³ requires mass in g and volume in cm³ — don't mix with kg/m³
Formula inversion: D = M ÷ V (not M ÷ D or V ÷ M) — use the triangle to check
Volume of irregular objects: Use displacement method — volume = water level rise in cm³
Confusing mass and weight: Mass is in kg/g; weight is a force in N — density uses mass

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Keep building this topic

Read this section alongside the surrounding pages in Density. That gives you the full topic sequence instead of a single isolated revision point.

Worked Example 2: Finding Mass What Is Density?Key Facts

Practice Questions for Density

Which formula correctly shows how density (D), mass (M) and volume (V) are related?

A. D = M + V
B. D = M × V
C. D = M ÷ V
D. D = V ÷ M

1 markfoundation

Explain what is meant by a density of 5 g/cm³.

2 marksstandard

Quick Recall Flashcards

Density Formula

Density = Mass ÷ Volume. Units: g/cm³ or kg/m³. Cover what you need in the triangle!

Floating Rule

Objects float if their density is LESS than the liquid. Water = 1 g/cm³, so anything under 1 g/cm³ floats.

14 questions on Density — practise free

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Worked Example 2: Finding Mass

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Density