What is the thermal energy change when 3 kg of a substance with a specific heat capacity of 500 J/kg°C is heated from 20°C to 50°C (Temperature changes in a system and specific heat capacity) (Temperature changes in a system and specific heat capacity; equation and unit focus: Calculate thermal energy change when mass, specific heat capacity and temperature change are known) (Temperature changes in a system and specific heat capacity; equation and unit focus: Calculate thermal energy change when mass, specific heat capacity and temperature change are known)

The correct answer is 45,000 J.

Particle lens: Describe arrangement, motion, spacing, collisions, or energy changes only when they are relevant here. This question asks: What is the thermal energy change when 3 kg of a substance with a specific heat capacity of 500 J/kg°C is heated from 20°C to 50°C (Temperature changes in a system and specific heat capacity) (Temperature changes in a system and specific heat capacity; equation and unit focus: Calculate thermal energy change when mass, specific heat capacity and temperature change are known) (Temperature changes in a system and specific heat capacity; equation and unit focus: Calculate thermal energy change when mass, specific heat capacity and temperature change are known). The correct response is 45,000 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 300 is distinct because it uses this exact question context and the particle lens rather than a generic particle-model sentence.