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AIR TEMPERATURE The air temperature at a height of \(h \mathrm{ft}\) from the surface of the earth is \(T=f(h)\) degrees Fahrenheit. a. Give a physical interpretation of \(f^{\prime}(h) .\) Give units. b. Generally speaking, what do you expect the sign of \(f^{\prime}(h)\) to be? c. If you know that \(f^{\prime}(1000)=-0.05\), estimate the change in the air temperature if the altitude changes from \(1000 \mathrm{ft}\) to \(1001 \mathrm{ft}\).

Short Answer

Expert verified
The derivative \(f'(h)\) represents the rate of change of air temperature with respect to altitude and has units of \(\dfrac{^{\circ}\text{F}}{\text{ft}}\). Generally, as altitude increases, air temperature decreases, so we expect \(f'(h) < 0\). Given \(f'(1000) = -0.05\), the estimated change in air temperature from 1000 ft to 1001 ft is \((-0.05)\times(1) = -0.05\,^{\circ}\text{F}\), a decrease of 0.05 degrees Fahrenheit.

Step by step solution

01

Part a: Physical Interpretation of \(f'(h)\)

The derivative \(f'(h)\) represents the rate of change of the air temperature with respect to the altitude \(h\). In other words, \(f'(h)\) tells us how the air temperature changes as we move 1 ft vertically. The unit of \(f'(h)\) is degrees Fahrenheit per foot, which is written as \(\dfrac{^{\circ}\text{F}}{\text{ft}}\).
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Part b: Expected Sign of \(f'(h)\)

Generally, as we go up into the atmosphere, the air temperature tends to decrease. Therefore, we expect the rate of change of temperature to be negative. In other words, we expect \(f'(h) < 0\).
03

Part c: Estimating Change in Temperature

We are given that \(f'(1000) = -0.05\). This means that the rate of change of temperature at \(h = 1000\text{ft}\) is -0.05 degrees Fahrenheit per foot. To estimate the change in air temperature when the altitude changes from 1000 ft to 1001 ft, we can use the rate of change at 1000 ft. Change in temperature = \(f'(1000) \times \Delta h\) Here, \(\Delta h\) is the change in altitude, which is \(1001 - 1000 = 1\text{ft}\). Change in temperature = \((-0.05)\times(1) = -0.05\,^{\circ}\text{F}\). So, the air temperature is estimated to decrease by 0.05 degrees Fahrenheit as the altitude changes from 1000 ft to 1001 ft.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Derivative Interpretation
In applied mathematics, a derivative gives us invaluable insight into how a function behaves. The derivative of a function at a particular point, like our function of temperature with respect to altitude, signifies how the function is changing at that very moment. Here, if we have the function \( T = f(h) \), the derivative \( f'(h) \) indicates how the air temperature changes as altitude changes.

It's like asking a friend what happens to the temperature if he climbs a ladder up a foot. If he tells you the temperature drops 0.05 degrees Fahrenheit each foot, he's giving you the derivative \( f'(h) \). It's measured in degrees Fahrenheit per foot \(\left( \frac{\text{°F}}{\text{ft}} \right)\).
  • It records the rate of temperature change per unit of height.
  • Helps predict what happens at small changes in altitude.
A positive derivative would imply a rise in temperature with increasing altitude, while a negative one suggests a decrease.
Rate of Change
The rate of change refers to how one quantity changes in relation to another. In our exercise, it tells us how the temperature changes as the altitude changes.

The rate of change concept is central to the understanding of derivatives. Whenever you calculate a derivative, you're essentially finding a rate of change. If \( f'(h) = -0.05 \), it means for each foot you ascend, the temperature decreases by 0.05 degrees Fahrenheit.
  • If \( f'(h) > 0 \), temperature goes up when climbing.
  • If \( f'(h) < 0 \), as in our case, temperature drops as you go higher.
This understanding can be handy for pilots or mountaineers because they can estimate temperature at different altitudes swiftly.
Altitude and Temperature Relationship
Altitude and temperature share an intricate relationship, often observed in atmospheric studies. Earth's atmosphere tends to cool as you ascend. The exercise brought up highlights this principle with \( f'(h) < 0 \), indicating a drop in temperature as altitude increases.

When climbing mountains or flying airplanes, this observation is crucial. Let's visualize it:
  • Imagine an ascending airplane: The temperature inside the cabin slightly compensates, but outside, it gets colder.
  • Usually, higher altitudes have thinner air, leading to lower temperatures due to lesser air pressure.
For every 1000 ft ascended, a notable temperature difference can often be detected. Recognizing this relationship can be vital for planning in aviation or even preparing for high-altitude treks.

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