The difference in cooling temperatures between the aluminum and water can be explained by their respective specific heat capacities. Specific heat capacity is the amount of heat energy required to raise the temperature of a substance by a certain amount.
In this case, aluminum has a lower specific heat capacity compared to water. This means that aluminum requires less heat energy to raise its temperature by a certain amount compared to water. Therefore, when both substances were warmed to 75 degrees Celsius, the aluminum absorbed less heat energy than the water.
When the containers were opened, both substances started losing heat to the surrounding environment. However, because the aluminum had absorbed less heat energy to begin with, it also released less heat energy during the cooling process. As a result, its temperature dropped more quickly and reached 35 degrees Celsius after one hour.
On the other hand, the water, which had absorbed more heat energy due to its higher specific heat capacity, released more heat energy during the cooling process. Consequently, its temperature dropped more slowly and only reached 66 degrees Celsius after one hour.
In summary, the lower specific heat capacity of aluminum compared to water resulted in it cooling down more quickly and reaching a lower temperature in the given time period.