If 3 kg of water is heated and its temperature increases from 20 °C to 80 °C, calculate the thermal energy change. The specific heat capacity of water is 4200 J/kg°C (Temperature changes in a system and specific heat capacity)

The thermal energy change is 75600 J.

Evidence lens: Use the data, graph feature, practical observation, or particle behaviour that proves the answer. This question asks: If 3 kg of water is heated and its temperature increases from 20 °C to 80 °C, calculate the thermal energy change. The specific heat capacity of water is 4200 J/kg°C (Temperature changes in a system and specific heat capacity). The correct response is The thermal energy change is 75600 J., because density links mass and volume, so the answer must preserve which quantity is being calculated. In Temperature changes in a system and specific heat capacity, the marking point should connect directly to calculate thermal energy change when mass, specific heat capacity and temperature change are known. If the question includes values, the working must keep the appropriate unit and operation; if it is an explanation, it must name the relevant particle behaviour or energy change. This item belongs to Internal energy and energy transfers, so avoid answers that switch to a different quantity, confuse heat with temperature, or describe gas pressure without collisions when collisions are the reason. Checkpoint 297 is distinct because it uses this exact question context and the evidence lens rather than a generic particle-model sentence.