Question

The specific heat of concrete is greater than that of soil. Given this fact, would you expect a major-league baseball field or the parking lot that surrounds it to cool off more in the evening following a sunny day?

Answer 1

The baseball field will cool off more.

Explanation:

The key to this problem lies with the definition of specific heat.

As you know, a substance's specific heat tells you how much heat much be added or removed to `"1 g"` of that substance in order to produce a change in temperature of `1^@"C"`.

More specifically, specific heat will tell you

• how much heat must be added in order to increase the temperature of `"1 g"` of a substance by `1^@"C"`

• how much heat must be removed in order to decrease the temperature of `"1 g"` of a substance by `1^@"C"`

So, what does the fact that concrete has a greater specific heat than soil tell you?

Well, a greater specific heat means that you need more heat to increase the temperature of `"1 g"` of concrete by `1^@"C"` than you need to increase the temperature of `"1 g"` of soil by `1^@"C"`.

Likewise, more heat must be given off by `"1 g"` of concrete in order for its temperature to decrease by `1^@"C"`.

Assuming that the parking lot and the soil get the same amount of heat from the sun on a given sunny day, you can conclude that the temperature of the concrete will increase by a smaller amount then the temperature of the soil.

At the end of the day, the concrete will be at a lower temperature than the soil.

Once night sets in, the exact same principle applies. The concrete will lose less heat then the soil, which means that the baseball field will cool off more then the parking lot.

In other words, the temperature swing will be greater for the soil than for the concrete, given the same amount of heat added during the day and removed during the night.