Final answer:
The roast will cool down as heat moves from the higher temperature roast to the lower temperature refrigerator. Food safety guidelines recommend keeping perishable foods at temperatures below 40 degrees Fahrenheit.
Step-by-step explanation:
When a roast at 160 degrees Fahrenheit is placed into a refrigerator with a temperature of 45 degrees Fahrenheit, the roast will start to cool down. Heat always travels from areas of higher temperature to areas of lower temperature. In this case, the heat in the roast will move towards the colder temperature in the refrigerator.
The rate at which the roast cools down depends on factors like the initial temperature difference, the mass of the roast, and the insulation properties of the refrigerator. Generally, as the roast is exposed to the lower temperature in the refrigerator, its temperature will gradually decrease until it reaches equilibrium with the surrounding temperature.
It's important to note that food safety guidelines recommend keeping perishable foods at temperatures below 40 degrees Fahrenheit to prevent bacterial growth. Therefore, putting the roast in the refrigerator at 45 degrees Fahrenheit would help maintain its freshness and safety.