Project 6 Name: Christian Lau

The Half-life of Pennies Lab Partner(s):

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Introduction:The half-life of a radioactive sample is the time required for half of the original sample of nuclei to decay. This lab activity uses pennies to make a model of the behavior of radioactive nuclides.

Prelab Assignment:1) Read through the lab thoroughly.2) Answer the following questions in complete sentences:

a. In this model, what do the pennies that land on “heads” represent?

__Those atoms which have decayed

b. In this model, what do the pennies that land on “tails” represent?

Those atoms that have not yet decayed

c. In this model, what does each flip represent?_One half life.

Materials:

100 penniesGraph paper

Purpose: To understand how to determine which function best models half life data.

Procedure: 1. Flip 100 pennies and separate them according to which landed heads and

which landed tails. Record the number of heads.

2. Flip only the pennies that landed heads, and then separate the pennies according to which landed heads and which landed tails. Record the number of heads. Repeat this process until you run out of pennies.

Data/Observations:

Record your observations in the table below:

Trial Number

Number of Pennies Flipped

Log (Number of Pennies Flipped)

1 100 22 45 1.65323 20 1.34 6 .7785 2 .3016 1 078910

Cleaning UpClean all materials and wash your hands thoroughly.

Analysis and Conclusions: Answer the following in complete sentences.

1) Make a graph of the number of pennies you flipped versus the trial number.

2) Calculate the least square regression line for your data and add it to your scatterplot. Label the graph with the equation and the value of the correlation coefficient (r).

3) Make a residual graph for you data.

4) Make a graph of log(number of coins flipped) versus trial number.

5) Calculate the least square regression line for the above data and add it to your scatterplot. Label the graph with the equation and the value of the correlation coefficient (r).

6) Make a residual graph for you data

7) Using the above information describe the relationship between the number of pennies flipped and the trial number. Refer to al four graphs in your discussionThe relationship between the number of pennies flipped and the trial number is exponential, not linear. The Log of Decay v. Trial graph indicates that an exponential graph is most appropriate to model the half life data because it has a strong linear relationship with the data.