Question

how long will heat continue to flow from warm to cool? until the temperature of both substances is equal (equilibrium) until the weight of both substances is the same

Explanation:

Heat transfer occurs due to a temperature difference. According to the second law of thermodynamics, heat flows from a warmer body to a cooler body. This process continues until thermal equilibrium is reached. Thermal equilibrium means there is no temperature gradient between the two substances. Weight has no direct relation to the heat - flow process. Heat transfer is governed by temperature differences, not mass or weight differences.

Answer:

until the temperature of both substances is equal ("equilibrium")