Define density as mass per unit volume; recall and use the equation ρ = m / V
1.4 Density 📏
What is Density? 🏗️
Density, denoted by ρ, is the amount of mass packed into a given volume. Think of it like how crowded a room is. If many people (mass) fit into a small room (volume), the density is high. If only a few people fit into a large room, the density is low.
The Density Formula 💧
$$\rho = \frac{m}{V}$$
where m is mass (kg) and V is volume (m³).
Examples & Analogies 🌊
- Water has a density of about 1 kg m⁻³, so 1 kg of water occupies about 1 L.
- Lead is much denser than water, so a small lead block can weigh a lot.
- Imagine a sponge (low density) vs. a steel ball (high density).
Sample Calculation 📐
| Mass (kg) | Volume (m³) | Density (kg m⁻³) |
|---|---|---|
| 2.5 | 0.5 | 5 |
Exam Tips ✏️
• Always check units: mass in kg, volume in m³, density in kg m⁻³.
• If the problem gives density and mass, find volume: V = m/ρ.
• If it gives density and volume, find mass: m = ρV.
• Remember to convert units if needed (e.g., cm³ to m³).
• Use the crowded‑room analogy to decide if density is high or low.
Key Takeaways 📌
- Density = mass ÷ volume.
- Units: kg m⁻³.
- Higher density means more mass in the same volume.
- Use the formula to solve for any missing quantity.
Revision
Log in to practice.
11 views
0 suggestions