Question

1. choose the best answer.

sunlight is an example of a transfer of thermal energy by ____.
conduction
expansion
radiation
convection

1. choose the best answer.

ice cream melting in a warm bowl is an example of a transfer of thermal energy by ____.
convection
radiation
expansion
conduction

Explanation:

• Question 2:
• Conduction: Requires direct contact between materials. Sunlight travels through space (a vacuum) to reach Earth, so it's not conduction.
• Expansion: Is a property related to the change in size of a material with temperature change, not a mode of heat transfer.
• Radiation: Is the transfer of heat in the form of electromagnetic waves. Sunlight is electromagnetic radiation that transfers thermal energy.
• Convection: Involves the movement of fluids (liquids or gases). Sunlight's transfer doesn't rely on fluid movement.
• Question 3:
• Convection: Relies on fluid movement. Here, heat transfer is between the bowl (solid) and ice - cream (initially solid, then liquid), not through fluid - like bulk movement.
• Radiation: Is heat transfer via electromagnetic waves. The interaction between the bowl and ice - cream is more about direct contact.
• Expansion: Is about size change with temperature, not heat transfer mode.
• Conduction: Occurs when there is direct contact between materials. The warm bowl is in direct contact with the ice - cream, and heat is transferred from the bowl (higher temperature) to the ice - cream (lower temperature) through direct molecular interaction.

Answer:

1. C. radiation
2. D. conduction