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Suppose a forest fire spreads in a circle with radius changing at a rate of 5 feet per minute. When the radius reaches 200 feet, at what rate is the area of the burning region increasing?

Short Answer

Expert verified
The area of the burning region is increasing at the rate of \(2000\pi\) square feet per minute when the radius is 200 feet.

Step by step solution

01

Identify what to find and underlying principles

We want to find how the area of the burning region is increasing when the radius is 200 feet. The underlying mathematical concept we'll use here is derivative, which helps us find the rate of the changing quantities. The formula for the area of a circle is \(A = \pi r^2\).
02

Differentiate the area of a circle with respect to time

To find how the area is changing with respect to time, we first need to differentiate the formula for the area of a sphere with respect to time 't'. What we'll get is \(dA/dt = 2\pi r (dr/dt)\). Here, \(dA/dt\) is the rate of change of the area, \(dr/dt\) is the rate of change of the radius and 'r' is the radius of the circle.
03

Substitute in the known values

We are given that \(dr/dt = 5\) feet per minutes and we want to find \(dA/dt\) when the radius 'r' is 200 feet. Substituting these values into our equation we get \(dA/dt = 2\pi (200) (5)\).
04

Compute for the rate of change of the area

Solving the above equation will give us the rate at which the area of the burning region is increasing when the radius is 200 feet, which turns out to be \(dA/dt = 2000\pi\) square feet per minute.

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Key Concepts

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

Rate of Change
The rate of change is a fundamental concept in calculus that refers to how a quantity varies over time. In the context of our exercise, it tells us how quickly the area of the burning region grows. Here we focus on how the radius and subsequently the area change as time progresses. A change in the radius leads to a corresponding change in the area, and the rate at which these changes occur is what we're interested in. In our specific problem, since the radius of the forest fire increases at a steady rate of 5 feet per minute, we aim to determine how this consistent growth impacts the area. Understanding this rate helps us forecast other evolving conditions, crucial in emergency planning.
Derivative
The derivative is a powerful tool in calculus that measures how a function changes as its input changes. It's essential for understanding rates of change in mathematical terms. Think of a derivative as the slope of a curve at a particular point, which implies how steep or shallow the curve is. In our problem, we use the derivative to find out how fast the area of a circle is increasing as the radius changes over time. It allows us to express the rate of change of the area with respect to time, denoted as \(\frac{dA}{dt}\). This simplifies comparisons and predictions by providing a numeric value indicating how one variable affects another at an instant.
Area of a Circle
The area of a circle is a straightforward yet crucial formula in geometry. It is defined by \(A = \pi r^2\), where \(A\) stands for the area, \(\pi\) is a constant approximately equal to 3.14159, and \(r\) is the radius. This formula is pivotal because in our case, as the radius of the burning region changes, so does its area. By applying differentiation, we can extend this simple geometric idea to dynamic scenarios, such as expanding fire areas, making it useful for predicting and controlling real-world events. Understanding how the area changes with the radius is key for applications in various fields including environmental science and safety engineering.
Differentiation
Differentiation is a core concept in calculus, used to find the rate at which one quantity changes in relation to another. By differentiating the formula for the area of a circle, \(A = \pi r^2\), with respect to time, we derive the expression \(\frac{dA}{dt} = 2\pi r \frac{dr}{dt}\). Here, differentiation helps us transition from a static formula to a dynamic framework where we can determine how quickly an area changes as the radius changes over time. In real-life applications, this means we can predict how rapidly the area of a forest fire will increase, which is crucial for implementing effective response strategies and minimizing damage.

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