Question 1: Define internal energy in the context of the particle model of matter.

Answer: Internal energy is the total kinetic and potential energy stored within the particles of a substance due to their motion and interactions.

Question 2: Explain how increasing the temperature of a substance affects its internal energy at the particle level.

Answer: Increasing temperature increases the average kinetic energy of particles, which raises the internal energy of the substance.

Question 3: What is the primary mechanism by which internal energy increases when a substance is heated?

Answer: The primary mechanism is an increase in the particles' kinetic energy as they move faster.

Question 1: Calculate the increase in internal energy when 2 kg of water is heated, raising its temperature by 30°C. Specific heat capacity of water = 4200 J/(kg·°C).

Answer: 252000 J

Question 2: A sample of aluminium weighing 0.5 kg absorbs 1500 J of heat energy. If the specific heat capacity of aluminium is 900 J/(kg·°C), what is the temperature increase?

Answer: 1.67°C

Question 1: Describe a simple experiment to demonstrate that heating a substance increases its internal energy. Include the variables you would control and safety precautions.

Answer: A possible experiment involves using a heater to warm a known mass of water while measuring temperature change with a thermometer. Control variables include the mass of water and the power supplied to the heater. Safety precautions include avoiding direct contact with hot equipment and ensuring proper insulation to prevent burns.

Question 1: A 1.5 kg block of sulphur is heated from 25°C to 85°C, absorbing 45,000 J of heat. Calculate the specific heat capacity of sulphur.

Answer: 200 J/(kg·°C)

Question 2: If the internal energy of a substance increases as temperature rises, what can be inferred about the particles' motion and interactions?

Answer: Particles gain kinetic energy, moving faster; their interactions also increase, contributing to higher potential energy within the substance.

Question 1: Explain how understanding internal energy is important in designing efficient heating systems for homes.

Answer: Knowing how internal energy changes helps engineers optimise heating systems to minimise energy loss and ensure effective heat transfer, making systems more efficient and cost-effective.

Question 2: Describe how internal energy considerations are important in industries such as cooking or manufacturing.

Answer: In cooking, internal energy determines how quickly and evenly food heats. In manufacturing, controlling internal energy helps in processes like melting, welding, or heat treatment to achieve desired material properties.