Question 1: Define thermal energy store in your own words.

Answer: A thermal energy store is the amount of heat energy contained within an object due to the movement of particles.

Question 2: Name and briefly describe the three main mechanisms of heat transfer.

Answer: Conduction is heat transfer through solids by particle vibrations, convection involves the movement of fluid (liquid or gas), and radiation is heat transfer through electromagnetic waves.

Question 3: Explain why metals are good conductors of heat.

Answer: Metals have free electrons that transfer heat quickly through the metal, making them good conductors.

Question 1: A 500 g block of aluminum is heated from 20°C to 80°C. The specific heat capacity of aluminum is 900 J/kg°C. Calculate the amount of thermal energy stored in the aluminum block.

Answer: Amount of thermal energy = mass × specific heat capacity × temperature change = 0.5 kg × 900 J/kg°C × (80°C - 20°C) = 0.5 × 900 × 60 = 27,000 Joules

Question 2: If 10,000 Joules of heat is added to a substance with a mass of 2 kg and a specific heat capacity of 500 J/kg°C, what is the temperature change?

Answer: Temperature change = heat added / (mass × specific heat capacity) = 10,000 J / (2 kg × 500 J/kg°C) = 10,000 / 1,000 = 10°C

Question 1: Describe a simple experiment to investigate conduction of heat through different materials.

Answer: Place identical hot objects (e.g., metal rods of the same shape) made of different materials (copper, aluminum, plastic) in contact with a cold surface and measure the time it takes for each to cool down. The material that cools faster conducts heat better. Ensure safety by handling hot objects with tongs.

Question 2: Identify two variables that should be controlled in an experiment measuring how quickly different materials transfer heat.

Answer: Variables to control include the initial temperature of the hot object and the environment temperature.

Question 3: Outline safety precautions to take when conducting experiments involving hot objects and heat transfer.

Answer: Use tongs or heat-resistant gloves to handle hot objects, conduct experiments in a well-ventilated area, keep flammable materials away from heat sources, and wear safety goggles.

Question 1: A pot of water is heated on a stove. The initial temperature is 25°C, and after 10 minutes, it reaches 100°C. Describe the energy transfer process involved and explain how the water's thermal energy store changes.

Answer: Heat is transferred from the stove to the water mainly through conduction and convection. The thermal energy stored in the water increases as heat energy is absorbed, raising the particles' kinetic energy, which increases the water temperature from 25°C to 100°C.

Question 2: Explain why a metal spoon becomes hot faster than a plastic spoon when both are placed in a hot liquid.

Answer: Because metals are good conductors of heat, they transfer heat quickly from the hot liquid to the spoon, making it hot faster than plastic, which is a poor conductor.

Question 1: Describe how thermal energy stores are utilized in a thermal power plant to generate electricity.

Answer: In a thermal power plant, fuel is burned to produce heat, which heats water to create steam. The stored thermal energy causes the steam to expand and turn turbines, converting thermal energy into mechanical energy, which then drives generators to produce electricity.

Question 2: Suggest one way to improve energy efficiency in household heating systems related to thermal energy transfer.

Answer: Installing better insulation reduces heat loss, ensuring more thermal energy stays within the house, making heating more efficient.