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 random motion and interactions.

Question 2: Explain how the internal energy of a substance changes when it is heated.

Answer: When a substance is heated, energy is transferred to the particles, increasing their kinetic energy and potentially their potential energy, thus raising the internal energy.

Question 3: What is the main difference between internal energy and temperature?

Answer: Internal energy is the total energy stored within the particles, while temperature measures the average kinetic energy of the particles.

Question 1: A sample of water (mass = 0.5 kg) is heated, and its internal energy increases by 1,250 Joules. Calculate the specific internal energy increase per kilogram.

Answer: Specific internal energy increase = total energy increase / mass = 1250 J / 0.5 kg = 2500 J/kg.

Question 2: If 300 Joules of energy is added to 0.2 kg of aluminum, what is the increase in its internal energy per kilogram? (Specific internal energy)

Answer: Increase per kg = 300 J / 0.2 kg = 1500 J/kg.

Question 1: Describe a simple experiment to measure how internal energy of a gas changes when it is compressed.

Answer: A gas sample is contained in a sealed cylinder equipped with a pressure and temperature sensor. The gas is compressed slowly, and changes in pressure and temperature are recorded. The increase in temperature indicates an increase in internal energy due to work done on the gas.

Question 2: Identify the main variables that affect the internal energy of a substance during heating.

Answer: Variables include the amount of heat energy supplied, the mass of the substance, and the specific internal energy capacity of the material.

Question 3: List two safety precautions to consider when conducting experiments involving heating substances.

Answer: Use heat-resistant gloves and eye protection; ensure proper ventilation to avoid buildup of harmful fumes.

Question 1: A metal rod (mass = 0.3 kg) is heated from 20°C to 80°C, and its internal energy increases by 1800 Joules. Calculate the specific internal energy change in J/kg°C. Assume the temperature change is linear.

Answer: Temperature change = 80°C - 20°C = 60°C. Specific internal energy change = 1800 J / (0.3 kg * 60°C) = 1800 / 18 = 100 J/kg°C.

Question 2: Interpret the data: What does the increase in internal energy tell you about the energy transfer during heating?

Answer: The increase indicates that energy was transferred to the rod, raising the particles' kinetic and potential energies, thus increasing internal energy.

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

Answer: Knowing how internal energy changes helps in selecting materials and designing systems that maximize heat retention or transfer, improving energy efficiency.

Question 2: Describe a technological application that relies on controlling internal energy.

Answer: Refrigeration and air conditioning systems control internal energy by removing heat from a space, using compressors and coolants to transfer energy out of the environment.