Question

If there are 520 grams of radioactive material with a half life of 12 hours how much of the radioactive material will be left after 72 hours? Is the radioactive decay modeled by a linear function or an exponential function

Answer 1

16.25 grams are left

exponential

Explanation:

Half the material will decay every 12-hour period (the other half will remain).

Initial amount (at time t = 0): 520 grams

Time t = 12: 260 grams are left

Time t = 24: 130 grams are left

Time t = 36: 65 grams are left

Time t = 48: 32.5 grams are left

Time t = 72: 16.25 grams are left

Radioactive decay is modeled by an exponential function. The function can't be linear because for them, equal time steps would produce equal reductions in the amount of material.