This mini-lesson covers Theme B.1 — Thermal energy transfers (with B.2, the greenhouse effect): temperature and internal energy, specific heat capacity, latent heat and phase change, the three transfer mechanisms, and how greenhouse gases warm the Earth.
Work through each screen, answer the questions as you go (some are reasoning, some are calculations) and collect ⭐ stars. Watch for the HL flag on higher-level extensions. Press Start when you're ready.
Temperature (in kelvin) is a measure of the average kinetic energy of a substance's particles. The internal energy of a body is the total kinetic + potential energy of all its particles.
Two objects at the same temperature have the same average particle KE. A bath of warm water can hold far more internal energy than a spark at 1000 °C because it contains vastly more particles.
The specific heat capacity c is the energy needed to raise 1 kg of a substance by 1 K (no phase change). Water's is large: 4180 J kg⁻¹ K⁻¹.
Heat 0.50 kg of water (c = 4180 J kg⁻¹ K⁻¹) by 20 K.
Q = mcΔT = 0.50 × 4180 × 20 = 41800 J = 41.8 kJ
During a phase change (melting or boiling) the temperature stays constant — the energy goes into breaking bonds (particle potential energy), not raising KE.
Ice → water uses the specific latent heat of fusion (3.34 × 10⁵ J kg⁻¹ for water). Water → steam uses the larger latent heat of vaporisation. On a heating graph these appear as flat plateaus.
Tap an item, then tap the group it belongs to.
Theme B.2: the Sun radiates mostly short-wavelength (visible) light that warms the Earth. The Earth re-radiates longer-wavelength infrared. Greenhouse gases — CO₂, CH₄, H₂O and N₂O — absorb this infrared and re-emit it in all directions, keeping the surface warmer.
Each greenhouse gas absorbs infrared at wavelengths matching the natural vibration frequencies of its molecules. Raising their concentration enhances the effect — the physics behind global warming. The Earth's albedo (fraction of light reflected) also affects the balance.
Tap a statement on the left, then its match on the right.
Temperature: average particle KE; T(K) = θ(°C) + 273
Specific heat: Q = mcΔT (no phase change)
Latent heat: Q = mL; temperature constant during melting/boiling
Transfer: conduction (contact) · convection (fluid flow) · radiation (no medium)
Greenhouse effect: gases absorb & re-emit Earth's infrared, warming the surface
That completes Thermal Energy Transfers for IB Diploma Physics HL. Press Finish to see your score.
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