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February 6, 2016

Search: Physics - Half life

Number of results: 78,771

math
If a hen and a half lay an egg and a half in a day and a half, how many hens are needed to lay a dozen eggs in one day?
November 28, 2007 by New Girl 102

chemistry
follows first-order kinetics and has an activation energy of 244 kJ mol-1. At 684 K, k = 0.00000508 s-1. What is the half-life (min) for this reaction at 427 °C ? Round your answer to 3 significant figures. I really dont know what to do
November 19, 2010 by bobjahng2

Calculus
Skeletal remains had lost 81% of the C-14 they originally contained. Determine the approximate age of the bones. (Assume the half life of carbon-14 is 5730 years. Round your answer to the nearest whole number.) yr
July 12, 2013 by Anonymous

calculus
Skeletal remains had lost 70% of the C-14 they originally contained. Determine the approximate age of the bones. (Assume the half life of carbon-14 is 5730 years. Round your answer to the nearest whole number.)
March 2, 2014 by angie

Math
Skeletal remains had lost 84% of the C-14 they originally contained. Determine the approximate age of the bones. (Assume the half life of carbon-14 is 5730 years. Round your answer to the nearest whole number.)
April 5, 2014 by Vanessa

Chemistry
I need help with the following problem: A fabric remnant from a burial site had a 14 C:12 C ratio of 0.838 of the original value. How old is the fabric? (half-life of 14 C = 5370 years)
April 29, 2009 by Sophie

math
How long will it take a given quantity of carbon-14 to lose 99.9% of its radioactivity if the half life is 5730 years? The formula I have been given is Q=ae^rt This is using log and ln functions.
April 25, 2011 by Niki

Algebra 2
A 14 gram sample of a substance that's used to preserve fruit and vegetables has a k-value of 0.1092. Find the substance's half-life, in days. Round your answer to the nearest tenth.
May 7, 2013 by Tristan

MATHS
experiments show that radium disintegrates at a rate proportional to the amount of radium present at the moment . if half life is 1590 years what percentage will disappear in one year?
September 26, 2014 by NOEL

MATHS
please help me ...Experiments show that radium at rate proportional to the amount of radium present at the moment . if half life is 1590 years what percentage will disappear in one year ??
September 26, 2014 by NOEL

Physics
A thin, uniform rod is hinged at its midpoint. To begin with, one half of the rod is bent upward and is perpendicular to the other half. This bent object is rotating at an angular velocity of 6.8 rad/s about an axis that is perpendicular to the left end of the rod and parallel...
November 17, 2012 by greg

physics
A thin, uniform rod is hinged at its midpoint. To begin with, one-half of the rod is bent upward and is perpendicular to the other half. This bent object is rotating at an angular velocity of 7.1 rad/s about an axis that is perpendicular to the left end of the rod and parallel...
April 8, 2014 by Alex

chemistry
Use the following steps to balance the redox reaction below: Mg + Au+ Mg2+ + Au -Write the oxidation and reduction half-reactions. Make sure each half-reaction is balanced for number of atoms and charge. -Multiply each half-reaction by the correct number, in order to balance ...
February 8, 2012 by Adrian

Physics 2
Calculate the maximum height using the initial speed, half-time, and angle. The initial speeed is 9.8m/s, half time is 1.8, and the angle is 75.
April 13, 2015 by Jennifer

English
In “Wave,” Dale Wisely characterizes water as an element that a. gives life b. takes life c. gives and takes life d. is life
October 26, 2015 by Kaai97

English
In “Wave,” Dale Wisely characterizes water as an element that a. gives life*** b. takes life c. gives and takes life d. is life
October 26, 2015 by Kaai97

Chemistry
a compound decomposes with half life of 8seconds and is independent of concentration.how much time is consumed to convert the concentration of one sixteenth of its initial concentration?
October 23, 2012 by Maria

Chemistry 2
For a second order reaction A <--> B, calculate the t1/2 (half life) and the k(constant) and also fill in the blanks. A (concentration) t(time) 20 0 sec 10 ? 5 40 sec 3 ? ? 200 sec t1/2=? k=?
March 3, 2014 by Ivan

Chemistry
Iron -59 has a half -life of 45.1 days. How old is an iron nail if the Fe-59 content is 25% that of a new sample of iron? Show all calculations leading to a solution.
May 8, 2015 by Gloria

physics
bar subjected to gravity load (two segments) the bar in the fig has constant cross sectional area A .the top half of the bar is made of material with mass density and youngs module, the bottom half of the bar made of density and young module total length of bar is 2 when bar ...
May 1, 2013 by mehwish

physics
bar subjected to gravity load (two segments) the bar in the fig has constant cross sectional area A .the top half of the bar is made of material with mass density and youngs module, the bottom half of the bar made of density and young module total length of bar is 2 when bar ...
May 1, 2013 by mehwish

physics
bar subjected to gravity load (two segments) the bar in the fig has constant cross sectional area A .the top half of the bar is made of material with mass density and youngs module, the bottom half of the bar made of density and young module total length of bar is 2 when bar ...
May 1, 2013 by mehwish

Physics
The lower half of an inclined plane is rough the upper half being smooth a particle is allowed to slide from the top and is brought to rest by friction just as it reaches the bottom, find the ratio of the force of friction to the weight of the particle intermes of the ...
March 3, 2014 by Ermias Abebe

Physics
The lower half of an inclined plane is rough the upper half being smooth a particle is allowed to slide from the top and is brought to rest by friction just as it reaches the bottom, find the ratio of the force of friction to the weight of the particle intermes of the ...
March 3, 2014 by Ermias Abebe

Ethics
Which of the following answers to the meaning of life did Tolstoy hold prior to his change of heart and mind? my answer is A a. Life has no meaning, and we must embrace that fact. b. Life's meaning is to provide comfort for oneself and one's family. c. Life's meaning is to ...
February 18, 2014 by Annmarie

chemistry
use the nuclear decay equation to find out how much a 7mg sample of iodine 128 remains after 116 minutes if the half life of this isotope is 25 minutes.
October 12, 2010 by dela

science
12. Aluminum in blood plasma was shown to undergo a first order elimination reaction with a half-life of 160 days. If the initial concentration was 8.2 µg/L, how long will it take for the concentration to drop to 2.5 µg/L?
February 13, 2011 by dan

math
solve the problem. the half-life of 234U, uranium-234, is 2.52 multiplied by 105 yr. If 98.3% of the uranium in the original sample is present, what length of time (to the nearest thousand years) has elapsed?
July 26, 2011 by juliet

Chem
Radioactive 24Na with a half-life of 14.8 hours is injected into an animal in a tracer experiment. How many hours will it take for the radioactivity to fall to 12.5% of its original intensity? I am confused on what number to start with
August 27, 2013 by Colby

Science
A persistent organic pollutant is estimated to have a half-life of 30y. If 3 tonnes of the chemical exists in a polluted area today, how much of the chemical will remain after 120y.
December 19, 2013 by Lily

chemistry
If the breakdown half-life of a pesticide applied to a farmer’s field is 3.50 days, then what is the rate constant for this reaction? Assume the degradation reaction follows first order kinetics. The units are 1/d.
February 14, 2015 by danny

Chemistry
The strontium-87 isotopes stores in the body and decays by the process shown below. The half-life is 2.80hr. Suppose that 0.766 millicuries got into the body. How many mc will remain after 8.40 hr?
September 27, 2015 by Morgan

Chemistry
A half-cell that consists of a copper wire in 1.00 M CuNO3 solution is connected by a salt bridge to a half cell containing a 1.00 M X(II) acetate solution and an electrode of metal X. The voltage of the cell is 2.00 V, with metal X as the positive electrode. Calculate the ...
April 12, 2015 by JUNDY

physics
We have to do a lab in physics where we research and write on real life applications of momentum, the guidelines we have are Research Assignment: Application of Momentum in Real-Life Situations Task: Choose any real-life situation where the concept of momentum is involved and ...
March 24, 2015 by Al

Chemistry
a certain first order decomposition reaction has a half-life of 15.0 minutes. What is the rate constant for this reaction? what is the time it will take for the reaction to reach the 10% completion point?
October 24, 2012 by Josh

Chemistry
What is the half-life of sodium-24? Explain how you determined your answer. Sodium-24 decays by beta emission. Write a nuclear equation that shows the decay of sodium-24 and its products.
May 31, 2013 by Help plz....Chloe

science
1. What is the half-life of Strontium-90? Explain your answer. Honestly I don't know how to get this answer. I've looked it up and stuff, but I just found the answer not how to know what it is. A link or explanation would be greatly appreciated. Thanks.
February 27, 2014 by Rainshine

Science
How much of a radioactive material with a half-life of 12,000 years is left after 36,000 years of decay?
April 17, 2009 by Angie

chemistry
so if my graph is absorbance vs time in minute, then my half life formula should give me time in minute right?
May 17, 2010 by bme1

chm
An unknown radioactive substance has a half-life of 3.20 . If 34.8 of the substance is currently present, what mass was present 8.00 hours ago?
February 10, 2012 by cp

Chemistry
The half-life for the process 238 U --> 206 Pb is 4.5*10^9 yr. A mineral sample contains 66.0 mg of 238 U and 16.0 mg of 206Pb. What is the age of the mineral?
February 12, 2012 by gary

chemistry
Nitrogen-13 has a half-life of 10 minutes. Given a starting mass of 2.00 g of nitrogen-13, how many grams will remain at the end of 30 minutes?
June 19, 2012 by drew

Chemistry
Potassium-42 has a half life of 12.4 hours. How much of an 848 g sample of potassium-42 will be left after 62.0 hours? Please help me!!
December 11, 2012 by Cindy

Exponential decay
Show that if a radioactive substance has a half life of T, then the corresponding exponential decay function can be written as y=y0e^kt
September 4, 2014 by Adrianna

Chemistry
Assuming an element's half-life is 3.6 years. How much of 2 grams of the element would remain after 10.8 years?
October 24, 2014 by Chandler

Chemistry
If a 40 gram sample of radioactive isotope was present at 4pm, but a 5 gram sample remained at 4:30 pm, what is the half-life in minutes?
December 15, 2014 by Jason

Science
I need to know how much of a 2g sample of Technetium-99 would be left after 12 hours. The half life of Technetium-99 is 6 hours
January 14, 2015 by Victoria

chemistry
The radioactive isotope, phosphorus-32, has a half-life of 14.26 days. How much phosphorus-32 will remain after 60 days? Please help.
September 3, 2015 by Ken

Physics
At 08:00hrs a 2.7- m-long vertical stick in air casts a shadow 1.8 m long. If the same stick is placed at 08:00hrs in air in a flat bottomed pool of salt water half the height of the stick, how long is the shadow on the floor of the pool? (For this pool, n = 1.64.) I can't get...
May 27, 2008 by Katie

calculus
The half-life of Radium-223 is 11.43 days. If a sample has a mass of 900 mg, find the mass (in mg) that remains after 5 days
October 14, 2010 by Connor

College Algebra
Only 34% of the carbon-14 in a wooden bowl remains. How old is the bowl? (Carbon-14 has a half-life of 5,700 years.)
November 22, 2010 by Lexi

College Algebra
Only 27% of the carbon-14 in a wooden bowl remains. How old is the bowl? (Carbon-14 has a half-life of 5,700 years.)
December 1, 2010 by Laura Hieb

algebra
11) The Half-Life of Tylenol is approximately 3 hours. If you take 1000mg, how Tylenol much is left in your body after 4 hours?
December 9, 2010 by Mary

science
If I begin with 100 atoms, how many atoms will be left of carbon 12 in 17,190 yrs if the half life of C12 is 5,730 yrs?
April 4, 2012 by betty

Chemistry
A 1.50- gas sample at 722 and 25.0 contains 7.56 radon-220 by volume. Radon-220 is an alpha-emitter with a half-life of 55.6s
September 21, 2012 by Diamond

Chemistry
A sample of charcoal is found to have only 1/8th of Carbon-14. Half-life of Carbon-14 is 5730yrs, what is the age of the charcoal?
December 1, 2012 by Anonymous

integrated math
Suppose a laboratory has a 26 g sample of polonium-210. The half-life of polonium-210 is about 138 days.?
January 15, 2013 by sara

chemistry
if the amount of radioactive iodine-123 in a sample decreases from .400g to .100g in 26.2 hours, what is the half-life of iodine-123
April 18, 2013 by j

Chemistry
The half-life of 131I is 8.021 days. What fraction of a sample of 131I remains after 24.063 days? 1/2 1/4 1/8 1/16 Please help. Thank you
January 24, 2014 by Kiki

chemistry
A radioactive sample contains 2.45 g of an isotope with a half-life of 3.8 days. How much of the isotope in grams will remain after 11.4 days?
March 14, 2014 by Jacques

chemistry
The half-life of oxygen-15 is 124 s. If a sample of oxygen-15 has an activity of 4800 Bq, how many minutes will elapse before it has an activity of 600 Bq?
September 27, 2014 by Anonymous

calculus
The half-life of Radium-223 is 11.43 days. If a sample has a mass of 400 mg, find the mass (in mg) that remains after 6 days
October 14, 2014 by w

Math
The half life of Uranium 230 is 20.8 days. How long would it take for 20% of Uranium 230 to decay?
January 11, 2009 by J

Exponential Decay
the half-life of carbon-11 is 20 minutes. How long will it btake for 600g of carbon-11 to decay to 30g?
October 22, 2009 by Mark

math
39mg radioactive with 1/2 life is decay total in 2.5 years. How many mg it remain if half of the amount is decay in 2 years? Thank you!
June 18, 2010 by Marie

Chemistry
If the amount of raidoactive iodine-123 in a sample decreases from 0.4 to 0.1 g in 26.2 hours, what is the half-life of iodine-123?
November 14, 2010 by Erin

Chemistry
If the amount of radioactive iodine-123 in a sample decreases from 0.8 g to 0.1 g in 36.2 hours, what is the half-life of iodine-123
April 17, 2011 by Sara

Science
43Lb has a half life of 42 minutes. If you start with 100 grams, how many grams will you have after 84 minutes?
January 28, 2014 by Sabrina

chemistry
If 9.00 g of _27^60 Co (half-life = 5.30 y) are allowed to decay, how many grams would be left after 1.00 y and after 10.0 y? g after 1.00 y g after 10.0 y
April 23, 2015 by tarsa

Math
A plant fossil lost 40 % of its carbon-14. How old is the fossil? (Half-life of carbon-14 is 5730 years.)
November 17, 2015 by meriton

Chemistry
Ba-140 has a half life of 13.0 days. What fraction of a sample of Ba-140 will remain after 39 days? A. 1/8th B. 1/16th C. 1/2th D. 1/4th
May 23, 2010 by Charleze

chemistry
if you start with 100mg of radioactive material that has a half life of one hour, how many mg's of radioactive material would you have in 10.2284952 hours?
February 1, 2011 by carlos

Chemistry
Cobalt-60, which undergoes beta decay, has a half-life of 5.26 yr. How many beta particles are emitted in 190s by a 3.10mg sample of Co-60? What is the activity of the sample in Bq?
February 12, 2012 by gary

Chemistry
Cobalt-60, which undergoes beta decay, has a half-life of 5.26 yr. How many beta particles are emitted in 190s by a 3.10mg sample of Co-60? What is the activity of the sample in Bq?
February 12, 2012 by gary

Chemistry
Cobalt-60, which undergoes beta decay, has a half-life of 5.26 yr. How many beta particles are emitted in 190s by a 3.10mg sample of Co-60? What is the activity of the sample in Bq?
February 12, 2012 by Steven

Chemistry
Cobalt-60, which undergoes beta decay, has a half-life of 5.26 yr. How many beta particles are emitted in 190s by a 3.10mg sample of Co-60? What is the activity of the sample in Bq?
February 13, 2012 by Steven

math
only 5% of the carbon-14 in a small wooden bowl remains , how old is the bowl? Hint, half-life for carbon –14 us 5730 years
April 4, 2012 by martha

chem
the half life of oxygen-15 is 124 s. if a sample of oxygen-15 has an activity of 4000 Bq, how many minutes will elapse before it reaches an activity of 500Bq
June 5, 2012 by Anonymous

chemistry
a certain radioactive nuclide has a half life of 5.00 hour. Calcuate the decay rate for 1.000 mole of this nuclide __________ decay s-1
July 12, 2012 by eric

College Algebra
The half-life of a radioactive material is about 34.6 years. How much of a 1-gram sample of the material is left after 30 years?
October 20, 2012 by Anonymous

Chemistry
Calculate the time in which the activity of an element is reduced to 90% of its original value. The half-life period of the element is 1.4*10^10 years . Answer :- 2.13*10^9 years
November 20, 2014 by Harsh

Chemistry
How long will it take for a 18.0-g sample of iodine-131 to decay to leave a total of 2.25 g of the isotope? The half-life of iodine-131 is 8.07 days
August 23, 2015 by Jillian

Chemistry
The strontium-90 isotope decays by the reaction below. It has a half-life of 28 yr. If the initial activity of this isotope was 168dpm, what would the activity be after 28.0 yr?
September 27, 2015 by Morgan

Science
If a radioactive isotope has half life of 5 days,how long will it take for its radioactive strength to be a maximum of one thousandth,(1/1000) of its original value? Can anyone give me a VERY SIMPLE explanation of this please? Thank you.
January 29, 2011 by Korina

Calculus
The half-life of Kryponite-123 is 40 years. Suppose we have a 700-mg sample. Find the decay k, and the expected amount of Kryptonite left after 30 years. I need help setting this problem up.
March 23, 2015 by Ryan kustin

Chem
If compound X has a first-order half-life of 24 seconds, how long would you have to wait for only 33% of the original material to be left? Explain why not knowing original Molarity of X does not effect this problem.
July 21, 2015 by Jessica

Physics
An industrial worker accidentally inhaled a radioisotope with an activity of 0.200 kBq. The substance swallowed has a very long effective half-life and therefore the activity will not change significantly during the worker’s lifetime. Every decay of the isotope releases 1.12...
May 16, 2010 by Kirsten

Physics
An industrial worker accidentally inhaled a radioisotope with an activity of 0.200 kBq. The substance swallowed has a very long effective half-life and therefore the activity will not change significantly during the workers lifetime. Every decay of the isotope releases 1.12 x ...
May 17, 2010 by Anonymous

chemistry
If C14 has a half-life of 4,000 years, what fraction will be remaining after 36,000 years?
July 7, 2011 by g

chemistry
If there is a radiation that has a half life of 10 days and we have it for 110 days, what will be the fraction of radiation left?
July 10, 2011 by g

Chemistry
If there is a radiation that has a half life of 10 days and we have it for 110 days, what will be the fraction of radiation left?
November 6, 2011 by Jennifer

help
the half-life of a radium is 1690 years is 90 grams is present now, how much will be present in 70 years
December 2, 2011 by Anonymous

CHEM
An isotope has a half life of 56 days. It now has 10,000DPM/ml. What will its activity be 100 days from now?
April 17, 2013 by Jared

Math
half life of a drug in the bloodstream is 14 hours. By what factor does the concentration of the drug decrease in 22 hours?
December 14, 2013 by Clare

Physics
A gram of living plant material with Carbon-14 , decays at a rate of about 16 disintegrations per minute. When the plant dies, the Carbon-14 decays, with a half-life of 5600 years. A gram of the dead plant is found to decay at about 1 disintegration per minute. Calculate the ...
November 23, 2015 by Deidre

Chemistry
Strontium-85, used for bone scans, has a half-life of 64 {\rm d}.How long will it take for the radiation level of strontium-85 to drop to \frac{1}{8} of its original level?
April 27, 2011 by Help!!

Biology
The half life of carbon 14 is 5700 years. If the carbon 14 level measured in a fossilized bone has only 1/4 of the original amount, how old in the bone?
May 16, 2011 by Jennifer

Math/Calculus
After 5 days, a particular radioactive substance decays to 37% of its original amount. Find the half life of this substance. Is this right? Th= ln 2/ln(1/.37) x 5 days
October 17, 2011 by Christine

Biology
The half-life of carbon-14 is 5,700 years. If a sample originally had 26 g of carbon-14, how much would it contain after 22,800 years?
November 19, 2013 by Emily

biology
What geological process is used to explain how nearly identical animals that cannot swim, are found on continents separated by large oceans? What is the half-life of Uranium 238 and what did we use that radioisotope to date as the oldest item on Earth?
April 21, 2012 by Anonymous

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