Questions: When a hot object is in contact with a cold object A. their molecules collide, transferring KE from hot to cold. B. their molecules collide, but keep their original speed. C. their molecules collide, transferring KE from cold to hot. D. their molecules avoid each other.

Solution Steps

When a hot object is in contact with a cold object, heat transfer occurs due to the difference in temperature. This process involves the transfer of kinetic energy (KE) from the molecules of the hot object to the molecules of the cold object.

• Option A: This option states that molecules collide, transferring kinetic energy from hot to cold, which aligns with the basic principle of heat transfer.
• Option B: This option suggests that molecules collide but retain their original speed, which contradicts the concept of energy transfer.
• Option C: This option suggests that kinetic energy is transferred from cold to hot, which is incorrect as energy naturally flows from a higher temperature to a lower temperature.
• Option D: This option states that molecules avoid each other, which is not possible as molecular collisions are essential for heat transfer.

Based on the analysis, the correct description of the process when a hot object is in contact with a cold object is that their molecules collide, transferring kinetic energy from the hot object to the cold object.

Final Answer