As the speed of a train increases, the amount of power needed to maintain that speed increases, and the rate of power increase also increases. Let P = f(v) be the power, in megawatts, needed for the train to maintain a speed of v kilometers per hour. (a) Sketch a possible graph of f. (b) For each of the functions f, f', and f", decide whether the function is positive or negative, and explain your answers. (c) What requires a greater increase in power: increasing the train's speed from 100 to 150 kilometers per hour, or increasing the train's speed from 200 to 250 kilometers per hour? Explain, based on your answer to part (b).

Calculus: Early Transcendentals
8th Edition
ISBN:9781285741550
Author:James Stewart
Publisher:James Stewart
Chapter1: Functions And Models
Section: Chapter Questions
Problem 1RCC: (a) What is a function? What are its domain and range? (b) What is the graph of a function? (c) How...
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**Understanding Power and Speed Relationship in Trains**

**Introduction:**

As the speed of a train increases, more power is needed to maintain that speed. Furthermore, the rate of power increase also rises. Let \( P = f(v) \) represent the power, in megawatts, required for a train to maintain a speed of \( v \) kilometers per hour.

**Tasks:**

(a) **Sketch a Possible Graph of \( f \):**
- Visualize a graph where the x-axis represents speed \( v \) (in kilometers per hour) and the y-axis represents power \( P \) (in megawatts).
- The curve is expected to be upward-sloping, indicating that as speed increases, the power needed also increases. The curve might become steeper, depicting increasing rate of power consumption at higher speeds.

(b) **Evaluate \( f, f', \) and \( f'' \):**
- **\( f(v) \):** This function is positive since power required is a positive quantity as long as the train is moving.
- **\( f'(v) \):** The first derivative indicates the rate of change of power with respect to speed. This should also be positive, reflecting the increase in power needed as speed increases.
- **\( f''(v) \):** The second derivative reflects the rate of change of the rate of power increase. If \( f(v) \) becomes steeper, \( f''(v) \) is also positive, indicating that the rate of power increase is itself increasing.

(c) **Analyze Power Increase Needs:**
- Consider the power increase when speed shifts from 100 to 150 kilometers per hour compared to 200 to 250 kilometers per hour.
- Since \( f'(v) \) is increasing, a greater increase in power is likely required for the higher speed range (200 to 250 km/h), because the curve becomes steeper as speed increases.

This conceptual understanding helps analyze how increased speeds demand progressively more power, emphasizing efficiency considerations in train operations and design.
Transcribed Image Text:**Understanding Power and Speed Relationship in Trains** **Introduction:** As the speed of a train increases, more power is needed to maintain that speed. Furthermore, the rate of power increase also rises. Let \( P = f(v) \) represent the power, in megawatts, required for a train to maintain a speed of \( v \) kilometers per hour. **Tasks:** (a) **Sketch a Possible Graph of \( f \):** - Visualize a graph where the x-axis represents speed \( v \) (in kilometers per hour) and the y-axis represents power \( P \) (in megawatts). - The curve is expected to be upward-sloping, indicating that as speed increases, the power needed also increases. The curve might become steeper, depicting increasing rate of power consumption at higher speeds. (b) **Evaluate \( f, f', \) and \( f'' \):** - **\( f(v) \):** This function is positive since power required is a positive quantity as long as the train is moving. - **\( f'(v) \):** The first derivative indicates the rate of change of power with respect to speed. This should also be positive, reflecting the increase in power needed as speed increases. - **\( f''(v) \):** The second derivative reflects the rate of change of the rate of power increase. If \( f(v) \) becomes steeper, \( f''(v) \) is also positive, indicating that the rate of power increase is itself increasing. (c) **Analyze Power Increase Needs:** - Consider the power increase when speed shifts from 100 to 150 kilometers per hour compared to 200 to 250 kilometers per hour. - Since \( f'(v) \) is increasing, a greater increase in power is likely required for the higher speed range (200 to 250 km/h), because the curve becomes steeper as speed increases. This conceptual understanding helps analyze how increased speeds demand progressively more power, emphasizing efficiency considerations in train operations and design.
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