What happens to heat flow between two objects of different temperatures?

Heat flow between two objects with different temperatures occurs in accordance with the second law of thermodynamics, which states that heat naturally flows from an object at a higher temperature to one at a lower temperature. This transfer continues until thermal equilibrium is reached, meaning that both objects are at the same temperature.

In this context, when the choice indicates that heat moves from hot to cold until equilibrium, it correctly describes the natural direction of heat flow. This process helps to equalize the temperature differences between the two bodies, and once they reach the same temperature, the heat flow ceases.

The other choices can be understood with this principle in mind. The idea that heat could flow from the cold object to the hot one contradicts the established laws of thermodynamics. Similarly, saying that heat remains constant ignores the fact that heat transfer occurs as long as there is a temperature difference. Lastly, while it is true that a cooler object may absorb heat, this statement does not capture the overall directional flow and the equilibrium process that is characteristic of thermal interactions.