A bottle of water at room temperature is placed in a freezer for a short time. An identical bottle of water that has been lying in the sunlight is placed in a refrigerator for the same amount of time. What must you know to determine which situation involves more energy transfer?

The initial temperature of the bottle

Explanation:

Heat transfer in this case is temperature dependent. The bottles are identical, however, the initial temperatures are different. Let's express this mathematically:

Newton's law of cooling states that the rate of cooling is dependent on the temperature between the body and its surroundings. Thus,

where the initial temperature of the surface is given by T₀ and the surface temperature is given by Tx

k = conventional heat transfer coefficient.

From the equation, if the object is slightly hotter than its surroundings, then the temperature gradient will be great and the object cools faster.

If the temperature of the object is cooler, then the temperature difference is low and the object cools slowly.

a coal burning power plant

photocells convert light energy to electricity