Question 1: What is thermal energy, and how is it related to temperature?

Answer: Thermal energy is the energy possessed by a system due to the movement of its particles. It is related to temperature because higher temperatures indicate greater particle movement and thus more thermal energy.

Question 2: Describe the three main mechanisms by which thermal energy is transferred between objects.

Answer: The three main mechanisms are conduction (transfer through direct contact), convection (transfer through fluid movement), and radiation (transfer through electromagnetic waves).

Question 1: A 2 kg aluminum cup is heated from 20°C to 80°C. Calculate the amount of thermal energy gained by the cup. (Specific heat capacity of aluminum = 900 J/kg°C)

Answer: Amount of thermal energy = mass × specific heat capacity × temperature change = 2 kg × 900 J/kg°C × (80°C - 20°C) = 2 × 900 × 60 = 108,000 Joules.

Question 2: A metal rod absorbs 1500 Joules of thermal energy and has a temperature increase of 25°C. If the rod's mass is 3 kg and its specific heat capacity is 500 J/kg°C, verify if the energy transfer is consistent with these values.

Answer: Expected energy = 3 kg × 500 J/kg°C × 25°C = 3 × 500 × 25 = 37,500 Joules. Actual energy absorbed is 1500 Joules, which is inconsistent; thus, either the data is incorrect or not all energy was absorbed.

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

Answer: Set up identical metal rods made of different materials (e.g., copper, aluminum, steel) with one end heated using a heat source. Attach thermometers at equal distances from the heated end to measure temperature changes over time. Ensure safety by using heat-resistant gloves and safety glasses. Record the temperature rise to compare thermal conductivities.

Question 2: Identify three variables that could affect the rate of thermal conduction in a material and state how each could influence the result.

Answer: Material type (different materials have different conductivities), thickness of the material (thinner materials transfer heat faster), and temperature difference (larger differences increase transfer rate).

Question 1: A metal spoon placed in hot water at 80°C reaches 60°C after 5 minutes. The surrounding air temperature is 20°C. What does this data suggest about the spoon’s thermal transfer properties and the environment?

Answer: The spoon transfers heat from the hot water to the environment through conduction, convection, and radiation. The gradual temperature increase indicates moderate thermal conductivity. The environment's temperature influences the rate of heat loss.

Question 2: If a container of water cools from 90°C to 30°C over 30 minutes in a room at 20°C, what can be inferred about the heat loss process? Consider the possible mechanisms involved.

Answer: The water loses thermal energy primarily through conduction to the container, convection into the surrounding air, and radiation. The gradual cooling suggests a steady heat transfer process, with the rate depending on the temperature difference, surface area, and thermal properties of the container and environment.

Question 1: Explain how thermal insulation materials used in buildings help conserve energy. Mention at least two types of materials and their properties.

Answer: Thermal insulation materials reduce heat transfer between the inside and outside of buildings. Materials like fiberglass and foam have low thermal conductivity, trapping heat during winter and keeping heat out during summer, thus conserving energy.

Question 2: How does understanding thermal energy transfer benefit the design of electronic devices such as smartphones or computers?

Answer: Understanding thermal transfer helps in designing efficient heat dissipation systems like heat sinks and fans, preventing overheating, maintaining performance, and prolonging device lifespan. Managing thermal energy ensures devices operate safely within temperature limits.