Energy Resources and Energy Transfers
5 marks · NormalA metal saucepan is placed on a stove to heat water for cooking. The saucepan has a metal handle, but some are designed with a wooden covering on the handle.
State and explain which process is mainly responsible for transferring thermal energy from the flame to the water.
Explain why it is beneficial for the handle to have a wooden covering, using ideas about thermal conductivity.
Give the correct SI unit for energy.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a) Conduction; thermal energy is conducted through the metal base to the water.
(b) Wood is a poor thermal conductor (good insulator), so it slows down the transfer of heat from the hot pan to the handle, making it safer to hold.
(c) joule (J)
Show mark scheme and worked solution
Marking points
M1 (a) · 1 mark · States conduction as the main process.
A1 (a) · 1 mark · Explains thermal energy transfer from the flame to water through the metal by conduction.
B1 (b) · 2 marks · Explains the wooden covering reduces heat transfer; uses correct reasoning about poor conductor (insulator).
B2 (c) · 1 mark · Gives 'joule' (or 'J') as the unit of energy.
Worked solution
a) The main process is conduction. Heat is transferred from the flame to the pan base, then conducted through the metal into the water.
b) Wood is a poor conductor of heat, so the wooden covering prevents heat from quickly reaching the outer part of the handle, making it safer to hold by reducing the risk of burns.
c) The correct SI unit for energy is the joule (J).