Explore BrainMass

Explore BrainMass

    Half-Life

    A half-life is the time needed for a amount of radioactive material to fall to half the amount as measured in the beginning of the time period. It describes the property of radioactive decay or the quantity which exists after exponential decay.

    The half-life describes the quantity which has undergone exponential decay. The opposite to half-life is doubling time. The exponential decay half-life process can be described by three equations as seen below:

    N(t)= N_0 (〖1/2)〗^(t⁄t_(1⁄2) ) (1)
    N(t)= N_0 e^((-t)⁄τ) (2)
    N(t)= N_0 e^(-λt) (3)

    Where
    N0 is the initial quantity of the substance that will decay
    N(t) is the quantity that still remains after time t
    T1/2 is the half-life of the decaying quantity
    Τ is the mean lifetime of the decaying quantity
    Λ is the decay constant of the decaying quantity.

    For processes with two or more exponential-decay processes simultaneously the equation is as followed

    1/T_(1⁄2) = 1/t_1 + 1/t_2 +⋯

    © BrainMass Inc. brainmass.com March 19, 2024, 6:11 am ad1c9bdddf

    BrainMass Solutions Available for Instant Download

    Radioactive Decay with Half-Life Concept

    I need some help in determining the half-life: 1. A radioactive source has a half life of 74 days and an activity of 370 MBq. what was the activity 30 days ago? 2. A radioactive source has a half life of 60 days. what is the relative activity after one week? 3. An 11- Ci Ir- 192 source is recieved on August 20. Regulator

    A range of radioactive decay calculations and solutions

    1. A source has a half-life of 12 hours and an initial activity of 10mCi. After 4 days what is its activity? 2. Calculate the % of activity remaining in a source after 10 half lives. 3. a. A radionuclide decays 1% in one day. Calculate the half life. b. A radionuclide decays 70% in one day. Calculate the half life. 4. A

    Source activity

    An Ir-192 HDR unit has an activity of 8.6 Ci on May 2. The treatment time for a vaginal cylinder is 300 seconds. If the treatment time for a similar treatment is not to exceed 10 minutes, the source must be changed on: A. July 15 B. June 23 C. July 1 D. August 5

    Half life formulas

    Use the appropriate half life formula for the case described below. Discuss whether the formula is valid for the case described. Poaching is causing a population of zebras to decline by 8% per year. What is the half life of the population? If there are 10,000 zebras today, how many will remain in 60 years? Does

    Radioactive element decays

    A radioactive substance containing N(t) radioactive elements at time t decays according to the following rule: dN/dt = -kN with K > 0. Calculate the half-life T as function of k. T is definded as the time needed to decrease by a factor 2 the number of radioactive elements.

    Half life problem

    The half-life (the time required for the body to eliminate one-half of the total amount of caffeine) varies widely depending on factors such as: age; liver function; pregnancy; medications. In healthy adults, the half life is approximately 5 hours. Mr. Math LOVES McDonald's Diet Coke, and drinks the big 32oz one, which contains

    Nuclear Decay for Radioactive Sources

    Three radioactive sources each have activities of 1.0 micro Curies (Ci) at t=0. Their half lives are 1 sec, 1 hour and 1 day respectively a.) how many radioactive nuclei are present at each source when t=0 b.)how many nuclei of each source decay between t=0 and t=1sec c.)how many nuclei of each source decay between t=0

    Analysis of administration of drugs using differential eqns

    A drug that has an half life of 20 hours inside the human body and is administered intravenously (I.V.) into a patient. The rate of change of the drug in the body is proportional to the amount present. Write a differential equation explaining the rate of change of the quantity of the drug and determine the constant proportio

    Half-Life of a Mixture

    Would you help me with the following problem? An assay of an equilibrium ore mixture shows an atomic ratio for U-235 / Pa-231 of 3.04 X 10 ^6 . Calculate the half-life of U-235 from the assay data and the known half-life of Pa-231 (3.28 x 10^4 y). Ignore the Th(231) decay product.

    Exploring the decay of Plutonium 241

    Pu-241 is produced from neutron absorption by Pu-240 (which is produced by neutron absorption by Pu-239). Calculate the fractional in-growth of Am-241 from Pu-241 (i.e. number ratio Am-241/Pu-241) from time = 0 to 200 years. Pu-241 is the parent and Am-241 is the daughter.

    Land of Lostistan Inflation Rate

    In the land of Lostistan, the rate of inflation is 2%. This means that the value of money of Lostistan is continuously decreasing at a rate of 2% per year. (a) If a citizen of this country has a ten dollar bill in his pocket today, how much will those ten dollars be worth in ten years? (b) How much will ten dollars be worth

    Calculating Mass and Decay: Example Questions

    Part 1: (7-atomic mass)Be decays with a half-life of about (53-atmic mass) d. It is produced in the upper atmosphere, and filters down onto the Earth's surface. If a plant leaf is detected to have 374 decays/s of (7-atomic mass)Be, how many days do we have to wait for the decay rate to drop to 14.2/s? Part 2: Calculate

    Decay rates: Which of the statements are true about decay rates and half-life?

    Which of the following statements are true about decay rates and half-life? True False a large decay constant implies a long half-life True False in carbon dating, the radioactive isotope of carbon that is used is carbon-12 True False half-life is the time it takes for a radioactive sample to decay away to nothing

    PP1 chain in stars like the Sun

    Could you please explain the origin of each term in the uppermost equation in the file attached? (As the problem asks) Please explain also the origin of the number (2 and 1/2). H stands for Hydrogen and D for Deuterium. pp stands for proton-proton reaction and p-d for proton-deuterium reaction. The other 3 equations should help.

    Migration of Pesticide from Soil to Groundwater

    The following percentages of three pesticides added to a soil remained after increasing times. Time (days) Diazinon % Benefin % Terbutol % 0 100 100 100 15 18.7 no data no data 30 1.50 57.5 94.3 60 0.30 29.0 80.2 90 0.01 14.5 73.7 180 0.01 7.50 51.3 1) Fit the decomposition data f

    Determining Amount of Radioactive Waste Created: Example Problem

    A certain nuclear power plant produces radioactive waste in the form of strontium-90 at the constant rate of 500 pounds per year. The waste decays exponentially with a half life of 28 years. How much of the radioactive waste from the nuclear plant will be present after 140 years? (hint: Think of this as a survival and renewal pr

    Radioactivity

    Please help with the following problem. The number of unstable nuclei remaining after a time t=5.00 yr is N, and the number present initially is N 0. Find the ratio N/N0 for (a) ^14/6C (half-life=5730 yr), (b) ^15/8O (half-life=122.2x; use t=1.00h, since otherwise the answer is out of the range of your calculator), and (c) ^

    Fossilized dinosaur skull and carbon-14 decay

    A fossil dinosaur skull has been found in Montana and has been C-14 dated to be 73 million years old. Provide two scientifically based reasons to explain why C-14 dating cannot do this.

    The half-life of tritium is approximately 12 years.

    I have been stuck on this problem for ever! I am not good with ratios and I have no idea what equation I need to solve this problem. Please help, thank you. The half-life of tritium is approximately 12 years. What will be the molar ratio of tritium to helium-3 in a sealed sample after 25 years?

    Solar Energy - Rectangular building facing North

    Question 2 Building shape and orientation [12] It is stated that a rectangular building facing North (in the Southern hemisphere) is the most energy efficient shape and orientation for latitudes away from the equator. Explain in detail why this is the case. [6] If you build a new rectangular house facing North, make recomm

    Lorentz transformation, length contraction, and time dilation.

    My question is in three parts and asks for a relation between two space time intervals, an explanation of length contraction and time dilation, then an application of proper time. i) Two inertial frames O and O' are in standard configuration. Write down the two equations relating spacetime intervals Delta x' and Delta t' in