Essential University Physics
4th Edition
ISBN: 9780134988566
Author: Wolfson, Richard
Publisher: Pearson Education,
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Chapter 38.2, Problem 38.2GI
To determine
The fraction of the original
15 O
remains undecayed after one hour.
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This exercise uses the radioactive decay model.
The half-life of radium-226 is 1600 years. Suppose we have a 29-mg sample.
(a) Find a function m(t) = mo2-t/h that models the mass remaining after t years.
m(t)
1600
29 2
(b) Find a function m(t) = moe-rt that models the mass remaining after t years. (Round your r value to six decimal places
m(t) =
%3D
(c) How much of the sample will remain after 5000 years? (Round your answer to one decimal place.)
1 mg
(d) After how many years will only 17 mg of the sample remain? (Round your answer to one decimal place.)
X yr
The radioactive gas krypton-85, produced by nuclear power plants as well as volcanoes, is present in trace amounts in earth’s atmosphere. Its half-life is 10.8 years. Suppose a volcano released 250 g of krypton-85 in an eruption. How much would remain after (a) 10.8 years, (b) 15 years, and (c) 50 years? Round to the nearest tenth of a gram.
Radioactive substances follow a specific law of decay.
Namely, if you have a sample of some radioactive isotope,
the quantity left after a certain time, called the half-life and
denoted T1/2, is one-half of what you had initially. If you wait
a second half-life, then there will be half f what was left at
the end of the first half-life. Since 1/2-1/2 = 1/4, you will
have one-fourth of the original quantity left after two half-lives.
You can continue with this procedure to find the fraction of the
original sample that hasn't decayed after any number of half-
lives. However, this would become quite cumbersome if you
are interested in the quantity left after, say, 10 half-lives. In
this case, the quantity you are looking for would be found by
multiplying the original quantity by 10 factors or 1/2.
To solve this problem, we use exponents. An exponent, a
small number written above and to the right, tells you how
many copies of a particular number are multiplied together. In
our example,…
Chapter 38 Solutions
Essential University Physics
Ch. 38.1 - Prob. 38.1GICh. 38.2 - Prob. 38.2GICh. 38.3 - Prob. 38.3GICh. 38.4 - Prob. 38.4GICh. 38.5 - Prob. 38.5GICh. 38 - Prob. 1FTDCh. 38 - Prob. 2FTDCh. 38 - Prob. 3FTDCh. 38 - Prob. 4FTDCh. 38 - Why are iodine-131 and strontium-90 particularly...
Ch. 38 - Prob. 6FTDCh. 38 - Prob. 7FTDCh. 38 - Prob. 8FTDCh. 38 - Prob. 9FTDCh. 38 - Prob. 10FTDCh. 38 - Three radon isotopes have 125, 134, and 136...Ch. 38 - Prob. 12ECh. 38 - Prob. 13ECh. 38 - Prob. 14ECh. 38 - Prob. 15ECh. 38 - How many half-lives will it take for the activity...Ch. 38 - Prob. 17ECh. 38 - Prob. 18ECh. 38 - Prob. 19ECh. 38 - Prob. 20ECh. 38 - Prob. 21ECh. 38 - Find the total binding energy of oxygen-16, given...Ch. 38 - Determine the nuclear mass of nickel-60, given...Ch. 38 - Prob. 24ECh. 38 - Prob. 25ECh. 38 - Prob. 26ECh. 38 - Prob. 27ECh. 38 - Prob. 28ECh. 38 - Prob. 29ECh. 38 - Prob. 30ECh. 38 - Prob. 31ECh. 38 - Prob. 32ECh. 38 - Prob. 33ECh. 38 - Prob. 34ECh. 38 - Prob. 35ECh. 38 - Prob. 36ECh. 38 - Prob. 37ECh. 38 - Prob. 38ECh. 38 - Prob. 39ECh. 38 - Prob. 40ECh. 38 - Prob. 41ECh. 38 - Prob. 42PCh. 38 - Prob. 43PCh. 38 - Prob. 44PCh. 38 - Iron-56, with nuclear mass 55.9206 u, is among the...Ch. 38 - Prob. 46PCh. 38 - Prob. 47PCh. 38 - Prob. 48PCh. 38 - Prob. 49PCh. 38 - Nitrogen-13 is a 9.97-min-half-lifc isotope used...Ch. 38 - Prob. 51PCh. 38 - Prob. 52PCh. 38 - Prob. 53PCh. 38 - Prob. 54PCh. 38 - The table below lists reported levels of...Ch. 38 - Prob. 56PCh. 38 - Analysis of a Moon rock shows that 82% of its...Ch. 38 - Prob. 58PCh. 38 - Prob. 59PCh. 38 - Prob. 61PCh. 38 - Prob. 62PCh. 38 - Prob. 63PCh. 38 - Prob. 64PCh. 38 - Prob. 65PCh. 38 - Prob. 66PCh. 38 - Prob. 67PCh. 38 - Prob. 68PCh. 38 - Prob. 69PCh. 38 - Prob. 70PCh. 38 - Prob. 71PCh. 38 - Prob. 72PCh. 38 - Prob. 73PCh. 38 - Prob. 74PCh. 38 - Bismuth-209 and chromium-54 combine to form a...Ch. 38 - Prob. 76PCh. 38 - Prob. 77PCh. 38 - Prob. 78PCh. 38 - Prob. 79PCh. 38 - Prob. 80PCh. 38 - Prob. 81PCh. 38 - Prob. 82PCh. 38 - Prob. 83PCh. 38 - Prob. 84PCh. 38 - Prob. 85PCh. 38 - Prob. 86PPCh. 38 - Prob. 87PPCh. 38 - Prob. 88PPCh. 38 - Prob. 89PP
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- Material found with the body had a C-14 activity of about 0.215 Bq per gram of carbon, where the A0 = 0.23 Bq per gram. If the half-life of C-14 is 5730yrs, determine the age of the Iceman’s remains.arrow_forwardKrypton-81m (81mKr) is a radioactive isotope with a half-life of 13.1 s that is often used in pulmonary ventilation studies for the gamma (γ) particles it emits. How long after a patient is administered a dose of 81mKr does only 7 % of the isotope remain? (in s) (a) 39.30 s (b) 36.78 s (c) 0.20 s (d) 34.84 s (e) 50.26 sarrow_forwardThe half life for the decay of carbon-14 is 5.73*10^3 years. Suppose the activity due to the radioactive decay of the carbon-14 in a tiny sample of an artifact made of wood from an archeological dig is measured to be 15. Bq. The activity in a similar-sized sample of fresh wood is measured to be 16. Bq. Calculate the age of the artifact. Round your answer to 2 significant digits.arrow_forward
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