On the 11th of March, 2011, an earthquake along the eastern shore of Japan caused a tsunami, which
then damaged a nuclear power plant. Several radioactive elements were released into the air and ocean.
Use an exponential decay formula to model how long some of these elements can be expected to persist
in the environment.
4. Cesium-137 has a decay constant of
0.0231 (a 30 year half-life). If 20
pounds of cesium-137 were released
into the Pacific Ocean by the tsunami,
how much will still be there ten years
later?
5. Strontium-90 has a decay constant of
0.0248 (a 28 year half-life). If 80
pounds of strontium-90 were
released into the Pacific Ocean by the
tsunami, how much will be left in 75
years?
6. When strontium-90 decays, it transforms into yttrium-90, which has a half-life of
only 64 hours, (0.007302 years). If the decay constant of yttrium-90 is -94.93,
what percentage of a one-pound sample will be left after one month ( of a
year)?