A certain radioactive material decays exponentially. The percent, P, of the material left after years is given by P(t) = 100(1.2). a. Determine the half-life of the substance. b. How fast is the substance decaying at the point where the half-life is reached? The substance is decaying at a rate of about -3.8% per year at the time 9.12 years where the half-life is reached The substance is decaying at a rate of about -9.12% per year at the time 6.8 years where the half-life is reached The substance is decaying at a rate of about -9.12% per year at the time 3.8 years where the half-life is reached None of the above

A certain radioactive material decays exponentially. The percent, P, of the material left after years is given by P(t) = 100(1.2). a. Determine the half-life of the substance. b. How fast is the substance decaying at the point where the half-life is reached? The substance is decaying at a rate of about -3.8% per year at the time 9.12 years where the half-life is reached The substance is decaying at a rate of about -9.12% per year at the time 6.8 years where the half-life is reached The substance is decaying at a rate of about -9.12% per year at the time 3.8 years where the half-life is reached None of the above

University Physics Volume 3

17th Edition

ISBN:9781938168185

Author:William Moebs, Jeff Sanny

Publisher:William Moebs, Jeff Sanny

Chapter11: Particle Physics And Cosmology

Section: Chapter Questions

Problem 60P: Suppose you are designing a proton decay experiment and you can detect 50 percent of the proton...

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Suppose you are designing a proton decay experiment and you can detect 50 percent of the proton decays in a tank of water. (a) How many kilograms of water would you need to see one decay per month, assuming a lifetime of 1031 y? (b) How many cubic meters of water is this? (c) If the actual lifetime is 1033 y, how long would you have to wait on an average to see a single proton decay?
Enter the correct nuclide symbol in each open tan rectangle in Figure P43.25, which shows the sequences of decays in the natural radioactive series starting with the long-lived isotope uranium-235 and ending with the stable nucleus lead-207. Figure P43.25
(a) Estimate the mass of the luminous matter in the known universe, given there are 1011 galaxies, each containing 1011 stars of average mass 1.5 times that of our Sun. (b) How many protons (the most abundant nuclide) are there in this mates? (c) Estimate the total number of particles in the observable universe by multiplying the answer to (b) by two, since there is an electron for each proton, and then by 109, since there are far more particles (such as photons and neutrinos) in space than in luminous matter.
A chain of nuclear reactions in the Suns core converts four protons into a helium nucleus. (a) What is the mass difference between four protons and a helium nucleus? (b) How much energy in MeV is released during the conversion of four protons into a helium nucleus?
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1. A radioactive substance with an initial mass of 250 mg has a half-life of 1 year. a) Write an equation to relate the mass of radioactive material remaining to time b) What mass will remain after 10 years? c) How long will it take the initial sample to decay to 20% of its initial mass? (Please show how you arrived at your answer by showing all of your calculations.)
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