/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 63 Radii of Stars Astronomers infer... [FREE SOLUTION] | 91Ó°ÊÓ

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Radii of Stars Astronomers infer the radii of stars using the Stefan Boltzmann Law: $$E(T)=\left(5.67 \times 10^{-8}\right) T^{4}$$ where \(E\) is the energy radiated per unit of surface area measured in watts (W) and \(T\) is the absolute temperature measured in kelvins (K). (a) Graph the function \(E\) for temperatures \(T\) between \(100 \mathrm{K}\) and \(300 \mathrm{K}\) (b) Use the graph to describe the change in energy \(E\) as the temperature \(T\) increases.

Short Answer

Expert verified
The energy \(E\) increases rapidly as temperature \(T\) increases.

Step by step solution

01

Set Up the Function

First, we set up the function based on the given formula. The Stefan-Boltzmann Law states that \(E(T) = (5.67 \times 10^{-8}) T^{4}\). We will use this to calculate energy for different temperatures.
02

Choose Temperatures for Plotting

We need to choose values for the temperature \(T\) between 100 and 300 K to plot the function. For accuracy, select increments, such as every 20 K: 100, 120, 140, ..., 300 K.
03

Compute Energy Values

Calculate the energy \(E(T)\) for each temperature using the formula. For example, for \(T = 100 K\), substitute into the equation: \(E(100) = (5.67 \times 10^{-8}) (100)^4\), and compute accordingly for each temperature increment.
04

Plot the Function

Using the calculated energy values for each temperature, plot \(T\) on the x-axis and \(E(T)\) on the y-axis. Connect the points to form a curve.
05

Analyze the Graph

Observe the shape of the plotted curve. Describe how the energy \(E\) changes as the temperature \(T\) increases. Take note of any trends or patterns, such as steepness or curvature, indicating the relationship between energy and temperature.

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Key Concepts

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

energy radiation
Energy radiation is a fundamental concept for understanding how stars, including our Sun, emit energy into space. According to the Stefan-Boltzmann Law, the amount of energy a star radiates per unit of surface area is directly related to its temperature raised to the fourth power. This means that even small increases in temperature result in significant increases in energy output.
The formula given by the Stefan-Boltzmann Law is:
  • \(E(T) = (5.67 \times 10^{-8}) T^4\)
  • \(E(T)\) is the energy radiated per unit area (W/m²)
  • \(T\) is the temperature in kelvins (K)
This powerful relationship helps astronomers calculate and predict the behavior of stars based on their temperature. The law is universal, applicable to all black bodies—objects that perfectly absorb all radiation they receive, a model closely approximated by stars.
temperature in kelvins
The temperature of a star or any celestial object is measured in kelvins (K), which is the standard unit of absolute temperature in scientific studies. Unlike Celsius or Fahrenheit, the Kelvin scale starts at absolute zero, the point at which particles have minimal vibrational motion.
  • Absolute zero is 0 K, equivalent to -273.15°C or -459.67°F.
  • 1 Kelvin is equivalent to 1 degree Celsius.
Using kelvins ensures that the calculations involving temperature are consistent with the physical principles that govern thermodynamics and absolute zero laws. In our problem, we're interested in temperatures between 100 K and 300 K, a range that provides a glimpse into how cooler stars behave in terms of energy radiation.
graphing functions
Graphing functions is a powerful tool to visually represent the relationship between two quantities. In this case, we want to graph the function given by the Stefan-Boltzmann Law, which relates the energy radiated \(E(T)\) to the temperature \(T\) in kelvins. The process involves plotting various points where temperature values are on the x-axis and their corresponding energy values on the y-axis.
  • Select temperatures, such as 100 K, 120 K, up to 300 K.
  • Calculate \(E(T)\) for each temperature using the formula provided.
  • Plot these (T, E) points on a graph.
  • Connect the points to visualize the curve.
The resulting curve typically shows a steep upward trend, indicating that energy dramatically increases as temperature rises. This visual representation helps to better understand the exponential nature of the relationship between temperature and energy as dictated by the Stefan-Boltzmann Law.
astronomy
In astronomy, the Stefan-Boltzmann Law is an essential tool for determining various characteristics of stars, such as their size, temperature, luminosity, and even their age. By analyzing a star's energy radiation, astronomers can infer its temperature and use other relationships to calculate its radius or distance.
The energy radiated by stars influences numerous aspects within the cosmos. For example:
  • Determines the habitability of planets orbiting the star.
  • Affects the structure of galaxies.
  • Helps in determining the lifecycle of stars.
Understanding the specifics of energy radiation through mathematical functions and graphing not only deepens our comprehension of the individual behavior of stars but also informs broader cosmological theories and models.

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Most popular questions from this chapter

Graphing Functions Sketch a graph of the function by first making a table of values. $$r(x)=3 x^{4}$$

A man is running around a circular track that is 200 m in circumference. An observer uses a stopwatch to record the runner's time at the end of each lap, obtaining the data in the following table. (a) What was the man's average speed (rate) between 68 s and 152 s? (b) What was the man's average speed between 263 s and 412 s? (c) Calculate the man's speed for each lap. Is he slowing down, speeding up, or neither? $$\begin{array}{|c|c|} \hline \text { Time (s) } & \text { Distance (m) } \\ \hline 32 & 200 \\ 68 & 400 \\ 108 & 600 \\ 152 & 800 \\ 203 & 1000 \\ 263 & 1200 \\ 335 & 1400 \\ 412 & 1600 \\ \hline \end{array}$$

DISCUSS: Finding an Inverse "in Your Head" In the margin notes in this section we pointed out that the inverse of a function can be found by simply reversing the operations that make up the function. For instance, in Example 7 we saw that the inverse of $$f(x)=3 x-2 \quad \text { is } \quad f^{-1}(x)=\frac{x+2}{3}$$ because the "reverse" of "Multiply by 3 and subtract 2" is "Add 2 and divide by 3 ". Use the same procedure to find the inverse of the following functions. (a) \(f(x)=\frac{2 x+1}{5}\) (b) \(f(x)=3-\frac{1}{x}\) (c) \(f(x)=\sqrt{x^{3}+2}\) (d) \(f(x)=(2 x-5)^{3}\) Now consider another function: $$f(x)=x^{3}+2 x+6$$ Is it possible to use the same sort of simple reversal of operations to find the inverse of this function? If so, do it. If not, explain what is different about this function that makes this task difficult.

Graphing Functions Sketch a graph of the function by first making a table of values. $$H(x)=|x+1|$$

A family of functions is given. In parts (a) and (b) graph all the given members of the family in the viewing rectangle indicated. In part (c) state the conclusions that you can make from your graphs. \(f(x)=c x^{2}\) (a) \(c=1, \frac{1}{2}, 2,4 ; \quad[-5,5]\) by \([-10,10]\) (b) \(c=1,-1,-\frac{1}{2},-2 ;[-5,5]\) by \([-10,10]\) (c) How does the value of \(c\) affect the graph?

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