View the following link. (Note that this link will not work on the Firefox browser, but will function in the freely downloadable Brave & the Chrome Browsers)

https://phet.colorado.edu/sims/cheerpj/nuclear-physics/latest/nuclear-physics.html?simulation=radioactive-dating-game

Preparation

Review the lecture and text about the physics and process involved in radio-isotope dating.

Set Up Directions

1) Navigate to the link above.2) Familiarize yourself with the simulation interface.3) Use the tabs at the top to explore the simulations "Half Life", "Decay Rates", and "Measurement".

Preliminary Analysis

1) Use the equation for radioactive decay and solve for an algebraic expression for the time, "t" in terms of the half-life, , and the isotope ratio, . ___t = ________________

Measurement Directions

1) Click on the tab labeled "Dating Game".2) Use the Carbon-14 probe and make sure that the selection "Objects" is check-marked to fill out Table 1.3) Move the Probe icon to the various artifacts and record the percentage of the isotope left in each artifact listed in Table 1 column 3.4) Estimate the age of the indicated artifacts by moving the double headed green arrow in the graph at the top of the interface, to match the percent isotope data for that artifact. Record the estimated age of the artifact in Table 1 column 4. If you enter your estimate into the simulation interface it will confirm if your estimate is valid or not. In the case of the layer 2 human skull you will want to use the equation that you develop in the preliminary analysis to estimate it's age. If an isotope ratio is zero enter "unable to determine" for the estimated age (column 4) of Table 1.5) Use the Carbon-14 probe with the option "Air" check-marked, to measure the isotope percentage in the air and record this in the bottom row of Table 16) Remain in the "Dating Game". Use the Uranium-238 probe to fill out the remaining Table 2. Make sure that "Objects"not "Air" is check-marked.7) Estimate the age of the indicated artifacts by moving the double headed green arrow in the graph to match the percent isotope data and the record the estimated age of the artifact in Table 2 column 4.

Table 1 Estimated Age of Various Artifacts using Carbon-14

	Stratographic Layer	% C-14 Isotope Remaining in Artifact	Estimated Age (years)
Living Tree	Surface	100%	0
House	Surface	99.1%	60-90
Dead Tree	Surface	97.4%	180-260
Wooden Cup	Top (first) Layer	88.2	850-1200
Human Skull	Top (first) Layer	76.6%	1800-2600
Fish Skeleton	2nd Layer (from top)	14.4%	13,000-19,000
Human Skull	2nd Layer	.8%	32,000-48,000
Rock 1	3rd Layer	0%	Unable to Determine
Dinosaur Skull	3rd Layer	0%	Unable to Determine
Brown Rock (#5)	Bottom (5'th layer)	0%	Unable to Determine
Air	Above Surface	100%	0

Table 2 Estimated Age of Various Artifacts using Uranium-238

	Stratographic Layer	% U-238 Isotope Remaining in Artifact	Estimated Age (years)
Living Tree	Surface	0%	Unable to Determine
House	Surface	0%	Unable to Determine
Fish Skeleton	2nd Layer (from top)	0%	Unable to Determine
Human Skull	2nd Layer	0%	Unable to Determine
Rock 1	3rd Layer	97.9	110-160 MY
Dinosaur Skull	3rd Layer	0%	Unable to Determine
Rock (#2)	4'th Layer	96%	210-310 MY
Trilobyte fossil	4'th Layer	0%	Unable to Determine
Small Rock (#4)	Bottom Layer (5'th)	89.4%	580- 860 MY
Brown Rock (#5)	Bottom Layer (5'th)	82.3%	1.1- 1.5 BY

Analysis and Conclusion

Reflect on and be able to explain the carbon isotope ratio of the air, living and dead life-forms.