On notebook paper, write your name, date, class period and name of assignment
"Pennies Lab" in the upper right hand corner. Answer the following questions.
1. What does each run represent? Each run represents a half-life.
2. Describe the shape of the graph and trend (increasing, decreasing, linear, curving.
3. After two half-lives, how many radioactive pennies (heads) were left?
25 About
what percentage does this represent? 25%
4. How many radioactive half-lives will it take to reduce the radioactivity to about 12% of
the original amount? 3
5. Can you predict which penny in your pitcher will decay next? No, it is chance.
6. How does this graph model radioactive decay of any radioactive element? When we
graphed our data, our graph is very similar to the graphs we see in literature.
Half-life curve
7. Does the rate at which popcorn pops have a half-life? Why or why not?
No, the rate of popcorn popping does not model the meaning of a half-life. A popcorn
half-life would mean that during a very specific amount of time, for example 2 minutes,
half of the kernels would pop. During the next 2 minutes, then, half of the remaining
kernels would pop. And so on. That is not how it is. Popcorn pops almost all at once,
and then sometimes you get a few kernels that would probably never pop.