Final answer:
Granite would likely cool down to room temperature the fastest among equal masses of dry air, water, and granite, due to its moderate specific heat capacity and high thermal conductivity. Dry air would cool faster than water but slower than granite. Water, with its high specific heat capacity, would cool the slowest.
Step-by-step explanation:
The question involves the topic of heat transfer and the properties of different materials, specifically their specific heat capacities when cooling to room temperature. Given equal masses of dry air, water, and granite, we need to determine which material would reach room temperature the fastest. The rate at which a material cools down is inversely proportional to its specific heat capacity, which is the amount of heat energy required to raise the temperature of a unit mass of a substance by one degree Celsius. Water has a high specific heat capacity compared to dry air and granite, meaning it requires more heat to increase its temperature and conversely, holds onto heat longer before cooling.
Dry air has a lower specific heat capacity than water, which allows it to change temperature more rapidly. Granite also has a lower specific heat capacity compared to water, but it is generally higher than that of dry air. However, a key factor here is thermal conductivity. Granite has a higher thermal conductivity than air, which means it can transfer its heat to the surroundings more quickly. Therefore, in this scenario, granite would likely cool down faster than both dry air and water given its relatively moderate specific heat capacity and high thermal conductivity. Dry air would cool faster than water due to its lower specific heat capacity, but slower than granite because of granite's thermal conductivity advantage. Water, with its high specific heat capacity, would take the longest to reach room temperature.