AP Physics 2 Lab
Half-life
Objective
Using a Phet simulation, find the initial number of particles in a sample of polonium
Materials
List the materials you will use in the lab. You may want to draw a sketch showing the apparatus.
Data
Describe (in complete sentences) 1) the data you will collect (what measurements will you make?)
2) how you will collect the data? (what tools will you use?) and 3) how you will use the data. Show any
equations you will use to make calculations. Record the data in your data table. It is not necessary to write
an entire procedure.
Procedure
1.
Remove a polonium atom from the bucket. Record the approximate time it takes for the atom
to decay in the Data Table for Trial 1.
2.
Repeat Procedure 1 for a total of 30 polonium atoms.
Calculations
1.
Find the total time for the 30 decays. Using the half-life given in the simulation, how many halflives is this? Record the Total Time and the Number of Half-lives in the Data Table.
2.
Find the initial number of polonium atoms in the bucket. Record this value in the Data Table.
Analyze
1.
What type of decay is polonium to lead? Explain.
2.
The actual half-life of polonium is 1.6 x 10−4 s. The approximate age of the Earth is 4.5 billion
years. Since polonium (and several other radioactive elements) have such short half-lives, how is
it that the polonium created when the Earth was formed has not all disappeared?
3.
Give a brief description why the product of this decay (lead) is stable and polonium is not.
4.
How much energy is released in this decay if the mass of 212
84Po = 211.9889 u, the mass of
208
4
82Pb = 207.9766 u and the mass of 2He = 4.0026 u?
1
AP Physics 2
Half-life Data Table
Trial
Time (s)
Trial
Time (s)
Trial
1
11
21
2
12
22
3
13
23
4
14
24
5
15
25
6
16
26
7
17
27
8
18
28
9
19
29
10
20
30
Total Time (s)
Number of Half-lives
Initial Number of Polonium Atoms
2
Time (s)