Explain without the key

A school is choosing door handles for a cold corridor: brass, glass or plastic. (a) A pupil plans a test. She fits a brass rod 8 mm thick and a plastic rod 4 mm thick into the side of a tank of hot water. On each rod she sticks a drawing pin 6 cm from the tank: the pin on the brass rod with butter, the pin on the plastic rod with candle wax. Identify the two faults in her plan, and state how to put each one right. (b) Supplement. In a second test she lays a tile of each material, all the same size and 1 cm thick, on the same hot plate at 75 °C, and times how long the top of each tile takes to reach 40 °C. The table shows her results. Identify the group each material belongs to: good thermal conductor, in between, or thermal insulator. Use the data to justify the group you give to glass. (c) Supplement. A pupil writes: “Brass conducts better than glass because the particles of brass vibrate faster.” Explain why this is incorrect. (d) Supplement. A pupil says: “Water conducts thermal energy well, because its particles are close together, like the particles of a solid.” Explain why this is incorrect.

identify: name or select. state: give a concise answer. justify: support your answer with evidence or an argument. explain: give reasons and connect them to evidence.