gen-define-the-structure-of-earth-s-interior-and-give-one-short-d39d

Define the structure of Earth's interior and give one short worked example.

# Structure of Earth's Interior Earth consists of distinct layers based on composition and physical properties: ## Compositional Layers (by chemistry): 1. **Crust** (5-70 km thick) - solid, least dense, silicate rocks 2. **Mantle** (2,900 km thick) - solid, denser silicate rocks rich in iron/magnesium 3. **Core** (3,480 km radius) - iron-nickel alloy - Outer core: liquid - Inner core: solid ## Physical Layers (by mechanical behavior): 1. **Lithosphere** (0-100 km) - rigid, brittle 2. **Asthenosphere** (100-350 km) - plastic, partially molten 3. **Mesosphere** (350-2,900 km) - solid but flowing 4. **Outer core** (2,900-5,150 km) - liquid 5. **Inner core** (5,150-6,370 km) - solid --- ## Worked Example: Calculating Average Earth Density **Given:** Earth's mass = 5.97 × 10²⁴ kg, Earth's radius = 6,371 km **Find:** Average density of Earth **Solution:** - Volume of sphere: V = 4/3 πr³ - V = 4/3 π(6.371 × 10⁶ m)³ = 1.083 × 10²¹ m³ - Density = mass/volume - ρ = (5.97 × 10²⁴ kg)/(1.083 × 10²¹ m³) - **ρ = 5,510 kg/m³** or **5.51 g/cm³** This is significantly denser than crustal rocks (~2.7 g/cm³), confirming a dense metallic core exists.