"Ketchup left overnight on dinner plates has a longer half-life than radioactive waste."
--Wes Smith
Preparation
Pre-lab assignment 14 (*.html)
(Due 12:00 PM before start of lab)
Equipment
6-sided dice (10+ per student)
DataStudio(TM), on laptops/computer workstations
Random.org Dice Roller (*.html), Hamete Virtual Dice Server (*.html)
(or similar simulators)
Announcement
This is your last lab meeting. Lab reports from this lab are due at the end of this lab. No late last lab reports are accepted.
DataStudio Exponential Decay Curve Fit
(These instructions do not need to be included in your step-by-step procedure.)
- Start DataStudio, select Enter Data.
- Enter the toss number for the independent (x) parameter, and the activity values for the dependent (y) parameter.
- Select Fit, and Natural Exponent, and record the fit parameters "Scale Factor" A, "Y-Offset" B, and "Exponent" C. The exponential function fit is y = B + A*exp(-C*x), where y = R(t), "Scale Factor" A = R0, "Exponent" C = λ (the decay constant), and x = t.)
Decay Activity Procedure
Starting with 10 actual dice, roll all of them, and count all "1's" as decays. Record the number of decays (R0) for this t = 0 round. Discard the decayed dice in a "dead" bin, and do not roll them again. Using the remaining dice, repeat for subsequent rounds t = 1, 2, etc., and record the number of decays (not the number of remaining dice) for each round; remember to discard the decayed dice at the end of each round. Repeat for as many rounds as neceesary (not necessary to wait until the last die "decays") to find an experimental curve-fitted decay constant λ. Then start the decay process over with either the same number of initial dice (for repeatability), or a larger number of initial dice (real or simulated), up to at least 300 initial dice. (Do not merely "multiply" results to scale up to larger number of dice.)
Research Question
How does the variation in experimental decay constant λ values depend on the number of initial dice used?
Tasks
- Procedure
Write a step-by-step procedure on a whiteboard. Instructor will check it off for full credit before data collection. (It is okay to do some preliminary scratch work.) Procedure should be detailed enough for another Physics 205B student to reproduce your results, without having to "fill in the blanks." Instructor may instead make suggestions or corrections that need to be completed before your group can receive full credit. (This should primarily describe the specific method used to simulate large numbers of dice.)
- Data
Record your data on another whiteboard. Instructor will check it off for full credit before laboratory ends. Data should be detailed enough for another Physics 205B student to understand what relevant quantities were measured for interpretation later. Graphs may be plotted by hand on graph paper, or printed out from a computer.
Report Format
- Procedure (checked off by instructor, do not include in lab report)
- Data (checked off by instructor, include copy in lab report)
- Discussion/Conclusion
Describe how the data is used to answer the research question. Discussion should be detailed enough for another Physics 205B student to reproduce your results, given similar data.
Your report only needs to include a copy of the data, and the discussion/conclusion. Due at the end of this laboratory. No late lab reports accepted.
Preparation/Reflection Points
1 = Pre-lab reading assignment (graded for completion)
1 = Post-lab reflection assignment (graded for completion)
Report Points (due at end of this lab)
1 = Procedure (graded for completion during lab)
1 = Data (graded for completion during lab)
3 = Discussion/Conclusion/Report
3 = Complete, thorough, understandable
(Reproducible by another student from start-to-finish.)
2 = Minor, "resolvable" omissions--acceptable effort
(Some common-sense/intuitive steps missing.)
(Another student would need a few minutes in order to "fill in the blanks.")
1 = Major "problematic" omissions--minimally acceptable effort
(Some essential/critical steps missing.)
(Another student would need to ask questions in order to "fill in the blanks.")
0 = Unacceptable or no significant effort beyond original in-lab work
1 = Early bonus for report received by instructor up until first 10 minutes of next lab
Follow-up
Complete this week's post-lab assignment before the Final Exam.
Due at start of Final Exam
Post-lab assignment 14 (*.html)
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