Imagine two identical suitcases — one packed with feathers, the other with bricks. Same size, VASTLY different weights. That difference is density in action. Density tells you how much mass is "packed into" a given space. A small gold ring and a massive gold bar have the SAME density because they're made of the same stuff — density is a property of the MATERIAL, not the object. This is why ships made of steel (density 7800 kg/m³) can float — they're mostly filled with air, making their OVERALL density less than water!
Density Equation
ρ = m / V
Density (kg/m³) = Mass (kg) ÷ Volume (m³)
This introduction covers The Suitcase Test within Density for GCSE Physics. Revise Density in Particle Model for GCSE Physics with 13 exam-style questions and 30 flashcards. This topic shows up very often in GCSE exams, so students should be able to explain it clearly, not just recognise the term. It is section 1 of 13 in this topic. Use this introduction to connect the idea to the wider topic before moving on to questions and flashcards.
Practice questions for Density
What is the correct equation for density?
Explain why gases have a much lower density than solids, using ideas about particles.
Quick recall flashcards
Density equation
ρ = m/V
What is density?
Mass per unit volume of a substance. How much 'stuff' is packed into a given space.