A student carries out two separate experiments to investigate the transfer of thermal energy.
In the first experiment, she joins a copper cylinder and a wooden cylinder of the same diameter end-to-end. She wraps a sheet of paper tightly around the joint. She then heats the paper at the joint using a Bunsen burner flame. After a short time, she observes a burn mark on one side of the paper, as shown in the diagram.
Explain why the paper burns where it is in contact with the wood, but does not burn where it is in contact with the copper.
In the second experiment, she places a piece of ice at the bottom of a test tube and fills the tube with water. A heavy metal ring is placed on top of the ice to prevent it from floating. She heats the top of the water until it boils.
Explain why the ice at the bottom of the test tube remains frozen while the water at the top is boiling.
