Which expression represents the energy change when heating a mass m by a temperature rise ΔT with specific heat capacity c?

Get ready for the NCEA Level 1 Energy Test. Utilize flashcards and multiple choice questions with clear explanations and hints. Prepare for success!

Multiple Choice

Which expression represents the energy change when heating a mass m by a temperature rise ΔT with specific heat capacity c?

When you heat a mass m by a temperature rise ΔT, the energy that flows in as heat is proportional to how much substance you have (m), how much energy each kilogram needs per kelvin (c), and how big the temperature change is (ΔT). The relationship is Ethermal = m × c × ΔT. Here c is the specific heat capacity, with units J/(kg·K), so multiplying by mass in kilograms and by the temperature change in kelvin gives energy in joules. This means: - If you double the mass, you need twice as much energy. - If you double the temperature rise, you need twice as much energy. - If the material has a larger c, it takes more energy per degree of temperature change. For example, heating 1 kg of water (c ≈ 4184 J/(kg·K)) by 10 K uses about 41,840 J, while heating 1 kg of a material with c ≈ 900 J/(kg·K) by the same 10 K uses about 9,000 J. Expressions that omit m or c won’t give the correct energy because they miss one of these essential factors.

When you heat a mass m by a temperature rise ΔT, the energy that flows in as heat is proportional to how much substance you have (m), how much energy each kilogram needs per kelvin (c), and how big the temperature change is (ΔT). The relationship is Ethermal = m × c × ΔT. Here c is the specific heat capacity, with units J/(kg·K), so multiplying by mass in kilograms and by the temperature change in kelvin gives energy in joules.

This means:

  • If you double the mass, you need twice as much energy.

  • If you double the temperature rise, you need twice as much energy.

  • If the material has a larger c, it takes more energy per degree of temperature change.

For example, heating 1 kg of water (c ≈ 4184 J/(kg·K)) by 10 K uses about 41,840 J, while heating 1 kg of a material with c ≈ 900 J/(kg·K) by the same 10 K uses about 9,000 J. Expressions that omit m or c won’t give the correct energy because they miss one of these essential factors.

More practice questions