/*! 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 2 Radioactive decay: A scientist i... [FREE SOLUTION] | 91Ó°ÊÓ

91Ó°ÊÓ

Radioactive decay: A scientist is studying the amount of a radioactive substance present over a period of time. A plot of the logarithm of the amount shows a linear pattern. What type of function should the scientist use to model the original data?

Short Answer

Expert verified
The scientist should use an exponential decay function: \( A(t) = A_0 \cdot e^{-kt} \).

Step by step solution

01

Understanding the Problem

The problem indicates that the amount of a radioactive substance is studied over time, and the plot of its logarithm shows a linear pattern. This suggests the logarithm of the amount decreases linearly with time.
02

Identify the Function Type

When the logarithm of a quantity decreases linearly over time, it implies an exponential decay model in terms of the original amount. This is based on the property that the logarithm of an exponential function is a linear function.
03

Mathematical Representation

To mathematically express this, we denote the amount of substance as \( A(t) \). If \( \log(A(t)) \) is a linear function, then \( A(t) \) must be in the form \( A(t) = A_0 \cdot e^{-kt} \), where \( A_0 \) is the initial amount and \( k \) is a positive rate constant.
04

Conclusion

Since the logarithm of the amount is linear, the scientist should use an exponential decay function to model the original data, given by \( A(t) = A_0 \cdot e^{-kt} \). This model accurately reflects the linear decay pattern observed in the log plot.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!

Key Concepts

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

Radioactive Decay
Radioactive decay is a fascinating process often encountered in physics and chemistry. It describes how unstable atomic nuclei lose energy by emitting radiation. This is a natural, spontaneous process where a radioactive isotope, over time, transforms into a different element or a different isotope of the same element.

During radioactive decay, atoms break down at a rate that is proportional to the number of atoms present. This leads to a decline in the quantity of radioactive material. Importantly, this decay process can be used to measure the ages of objects, such as the famous carbon dating technique used for archaeological finds.

Understanding the decay pattern helps scientists model how much of a substance remains at any given time. The predictable nature of radioactive decay makes it a perfect fit for certain types of exponential mathematical models, helping us better understand and predict the behavior of these materials over time.
Linear Pattern
Here comes the magic of patterns in data! A linear pattern means that data points align to form a straight line when plotted on a graph. This is easy to visualize and understand.

In the context of the problem, when the logarithm of the amount of a radioactive substance follows a linear pattern, it suggests a consistent rate of decay. This reveals important properties about the material. Such patterns simplify the process of analysis, making it easier for scientists to establish relationships and create mathematical models to describe the system.

Think of it as connecting the dots—once all the dots (or data points) are connected in a straight line, we can easily predict further tendencies, providing valuable insights into the process being studied.
Logarithmic Function
Logarithmic functions are a key player in understanding exponential decay processes. A logarithm answers the question: To what power must we raise a specific base to get a certain number? For those curious minds, the most commonly used base in these scenarios is the number "e" (approximately 2.718).

A beautiful property of logarithms is transforming multiplicative relationships into additive ones. Thus, when we take the logarithm of an exponential decay process, it reveals a linear pattern. This transformation simplifies complex multiplicative processes of decay into straightforward addition that can be modeled easily.

This characteristic allows scientists to take complex exponential data and convert it into a simpler linear form, making it easier to analyze and interpret the information they gather from experiments.
Mathematical Modeling
Mathematical modeling is akin to creating a blueprint or recipe that helps predict future occurrences. It involves using mathematical expressions and computations to simulate real-world scenarios and systems.

When dealing with radioactive decay, creating a model that accurately predicts how a substance will behave over time is crucial for interpretation and planning. This involves the application of functions and equations, such as the exponential decay model.

This model is not just a theoretical exercise; it has practical applications too! For example, predicting the remaining quantity of a radioactive substance after a certain period empowers researchers and policymakers with vital information about safety, environmental impact, and resource management.
Rate Constant
The rate constant is an important parameter in the equations governing radioactive decay. Picture it as a dial that controls how fast something changes over time.

In the exponential decay function, the rate constant, denoted as "k", determines the speed at which the amount decreases. If the amount of substance decreases faster, "k" will be larger. Conversely, a slower decay rate means a smaller value of "k".

Understanding and calculating this rate constant is crucial because it defines the shape and slope of the decay curve. It’s similar to having a stopwatch to time the rate of change in a process; thus, this parameter helps scientists predict how rapidly a radioactive substance will vanish, allowing for informed decisions and planning.

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

. The half-life of U239: Uranium 239 is an unstable isotope of uranium that decays rapidly. In order to determine the rate of decay, 1 gram of U239 was placed in a container, and the amount remaining was measured at 1-minute intervals and recorded in the table below $$ \begin{array}{|c|c|} \hline \begin{array}{c} \text { Time } \\ \text { in minutes } \end{array} & \begin{array}{c} \text { Grams } \\ \text { remaining } \end{array} \\ \hline 0 & 1 \\ \hline 1 & 0.971 \\ \hline 2 & 0.943 \\ \hline 3 & 0.916 \\ \hline 4 & 0.889 \\ \hline 5 & 0.863 \\ \hline \end{array} $$ a. Show that these are exponential data and find an exponential model. (For this problem, round all your answers to three decimal places.) b. What is the percentage decay rate each minute? What does this number mean in practical terms? c. Use functional notation to express the amount remaining after 10 minutes and then calculate that value. d. What is the half-life of U239?

Cell phones: The following table shows the number, in millions, of cell phone subscribers in the United States at the end of the given year. $$ \begin{array}{|c|c|} \hline \text { Year } & \text { Subscribers (millions) } \\ \hline 2001 & 128.4 \\ \hline 2002 & 140.8 \\ \hline 2003 & 158.7 \\ \hline 2004 & 182.1 \\ \hline 2005 & 207.9 \\ \hline \end{array} $$ a. Plot the natural logarithm of the data points. Does this plot make it look reasonable to approximate the original data with an exponential function? b. Find the regression line for the natural logarithm of the data and add its graph to the plot in part a. c. Construct an exponential model for the original subscribership data using the logarithm as a link.

$$ \begin{array}{|c|c|c|c|} \hline \text { Year } & \text { Wolves } & \text { Year } & \text { Wolves } \\\ \hline 1985 & 15 & 1993 & 40 \\ \hline 1986 & 16 & 1994 & 57 \\ \hline 1987 & 18 & 1995 & 83 \\ \hline 1988 & 28 & 1996 & 99 \\ \hline 1989 & 31 & 1997 & 145 \\ \hline 1990 & 34 & 1998 & 178 \\ \hline 1991 & 40 & 1999 & 197 \\ \hline 1992 & 45 & 2000 & 266 \\ \hline \end{array} $$ Gray wolves in Wisconsin: Gray wolves were among the first mammals protected under the Endangered Species Act in the \(1970 \mathrm{~s}\). Wolves recolonized in Wisconsin beginning in 1980 . Their population has grown reliably since 1985 as follows: \({ }^{21}\) a. Explain why an exponential model may be appropriate. b. Are these data exactly exponential? Explain. c. Find an exponential model for these data. d. Plot the data and the exponential model. e. Comment on your graph in part d. Which data points are below or above the number predicted by the exponential model?

Grains of wheat on a chess board: A children's fairy tale tells of a clever elf who extracted from a king the promise to give him one grain of wheat on a chess board square today, two grains on an adjacent square tomorrow, four grains on an adjacent square the next day, and so on, doubling the number of grains each day until all 64 squares of the chess board were used. How many grains of wheat did the hapless king contract to place on the 64th square? There are about \(1.1\) million grains of wheat in a bushel. Assume that a bushel of wheat sells for \(\$ 4.25\). What was the value of the wheat on the 64th square?

Long-term population growth: Although exponential growth can often be used to model population growth accurately for some periods of time, there are inevitably, in the long term, limiting factors that make purely exponential models inaccurate. If the U.S. population had continued to grow by \(3 \%\) each year from 1790 , when it was \(3.93\) million, until today, what would the population of the United States have been in 2000 ? For comparison, according to census data, the population of the United States in 2000 was \(281,421,906\). The population of the world was just over 6 billion people.

See all solutions

Recommended explanations on Math Textbooks

View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.