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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.

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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.

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Most popular questions from this chapter

Magazine sales: The following table shows the income from sales of a certain magazine, measured in thousands of dollars, at the start of the given year. $$ \begin{array}{|c|c|} \hline \text { Year } & \text { Income } \\ \hline 2001 & 7.76 \\ \hline 2002 & 8.82 \\ \hline 2003 & 9.88 \\ \hline 2004 & 10.94 \\ \hline 2005 & 12.00 \\ \hline 2006 & 13.08 \\ \hline 2007 & 14.26 \\ \hline 2008 & 15.54 \\ \hline \end{array} $$ Over an initial period the sales grew at a constant rate, and over the rest of the time the sales grew at a constant percentage rate. Calculate differences and ratios to determine what these time periods are, and find the growth rate or percentage growth rate, as appropriate.

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Grazing rabbits: The amount A of vegetation (measured in pounds) eaten in a day by a grazing animal is a function of the amount V of food available (measured in pounds per acre).15 Even if vegetation is abundant, there is a limit, called the satiation level, to the amount the animal will eat. The following table shows, for rabbits, the difference D between the satiation level and the amount A of food eaten for a variety of values of V. $$ \begin{array}{|c|c|} \hline V \text { = vegetation level } & D=\text { satiation level }-A \\ \hline 27 & 0.16 \\ \hline 36 & 0.12 \\ \hline 89 & 0.07 \\ \hline 134 & 0.05 \\ \hline 245 & 0.01 \\ \hline \end{array} $$ a. Draw a plot of D against V. Does it appear that D is approximately an exponential function of V ?

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