# Physics - Half life

86,865 results

Math
The half-life of 234U, uranium-234, is 2.52 105 yr. If 97.7% of the uranium in the original sample is present, what length of time (to the nearest thousand years) has elapsed? ? yr

algebra
The half-life of 234U, uranium-234, is 2.52 105 yr. If 97.7% of the uranium in the original sample is present, what length of time (to the nearest thousand years) has elapsed

algebra
The half-life of 234U, uranium-234, is 2.52 105 yr. If 97.7% of the uranium in the original sample is present, what length of time (to the nearest thousand years) has elapsed?

math
The half-life of 234U, uranium-234, is 2.52 105 yr. If 97.4% of the uranium in the original sample is present, what length of time (to the nearest thousand years) has elapsed?

algebra
The half-life of plutonium-234 is 9 hours. If 40 milligrams is present now, how much will be present in 4 days? (Round your answer to three decimal places.)

algebra
The half-life of 234U, uranium-234, is 2.52 105 yr. If 98.4% of the uranium in the original sample is present, what length of time (to the nearest thousand years) has elapsed?

math
The half-life of 234U, uranium-234, is 2.52 105 yr. If 98.3% of the uranium in the original sample is present, what length of time (to the nearest thousand years) has elapsed?

algebra
The half-life of 234U, uranium-234, is 2.52 105 yr. If 97.7% of the uranium in the original sample is present, what length of time (to the nearest thousand years) has elapsed?

College algebra
The radioactive element has a half-life of about 28 years and sometimes contaminates the soil. After 47 years, what percentage of a sample of the elements remain?

Chemistry 2
For the fist order reaction A <-> B, calculate the t1/2(half life) and k(rate constant) and also fill in the blanks. A-Concetration t-time 20 0 10 ? 5 40 sec 3 ? ? 500 sec t1/2=? k=?

Chemistry 2
For the fist order reaction A <-> B, calculate the t1/2(half life) and k(rate constant) and also fill in the blanks. A-Concetration t-time 20 0 10 ? 5 40 sec 3 ? ? 500 sec t1/2=? k=?

Chemistry
A first-order reaction has a half-life of 26.4 seconds. How long does it take for the concentration of the reactant in the reaction to fall to one-eighth of its initial value?

Math
A fossilized leaf contains 21% of its normal amount of carbon 14. How old is the fossil (to the nearest year)? Use 5600 years as the half-life of carbon 14.

Math
Suppose that the half-life of a substance is 250 yrs. .If there were initially 100 g of substance .How much will remain after 500 years??with solution please

physics
Calculate the maximum height using the initial speed, half-time, and angle. The initial speeed is 18m/s, half time is 1.8, and the angle is 75. And how is this written out to solve.

mechanics
The change in length of a steel wire under an applied load can be halved by keeping all other conditions constant but using: A. a different material having a Young's modulus half that of steel B half the cross sectional area of the steel wire C half the length of steel wire D ...

Chemistry
If 100.0 g of carbon-14 decays until only 25.0 g of carbon is left after 11,460 y, what is the half-life of carbon-14?

physics help!!
A body at given uniform temperature of 300K and internal energy 8x10^6 J is split in two equal halves: a)Has any heat been exchanged b)What is the temperature of each half? c)What is internal energy of each half? K=Kelvin

Chemistry
I don't know the correct answer that's what i have to find. for the first part here is my work..... 6.2e-4/min=0.0372seconds half life: t_1/2=0.693/0.372s =18.6sec*1min/60sec=0.310min (which is not right!)

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 don't know what to do

Chemistry
The half-life for the first-order conversion of A to B is 56.5 hours. How long does it take for the concentration of A to decrease to 10.0% of its original amount? Our professor has given us the answer - 188hr but I am not entirely sure how he got it.

physics
The bunny is initially hopping east at 7 m/s when it first sees the fox. Over the next half second the bunny changes its velocity to west at 12 m/s and escapes. What was the bunny's average acceleration (magnitude and direction) during this half-second interval?

chemistry
A 7.500-mg sample of chromium-55 is analyzed after 14.0 min. and found to contain 0.469 mg of chromium-55. what is the half-life of chromium-55?

chemistry
a 7.500-mg sample of chromium-55 is analyzed after 14.0 min and found to contain 0.469 mg of chromium-55. what is the half-life of chromium-55

How will your life experiences prove beneficial as you move through your degree program? Briefly describe two life experiences and illustrate how each will be useful as you pursue academic goals. How can you reject the negative influences in your life and benefit from the ...

maths lit, geography, life science, history, life orientation, english, tswana
what can I do with my life with all this subjects that I studied?.

math
The half-life of 234U, uranium-234, is 2.52 multiplied by 105 yr. If 97.7% of the uranium in the original sample is present, what length of time (to the nearest thousand years) has elapsed?

math
The half-life of 234U, uranium-234, is 2.52 multiplied by 105 yr. If 97.4% of the uranium in the original sample is present, what length of time (to the nearest thousand years) has elapsed?

algebra
The half-life of 234U, uranium-234, is 2.52 multiplied by 105 yr. If 98.8% of the uranium in the original sample is present, what length of time (to the nearest thousand years) has elapsed?

algebra
The half-life of 234U, uranium-234, is 2.52 multiplied by 105 yr. If 98.8% of the uranium in the original sample is present, what length of time (to the nearest thousand years) has elapsed?

algebra
The half-life of 234U, uranium-234, is 2.52 multiplied by 105 yr. If 98.6% of the uranium in the original sample is present, what length of time (to the nearest thousand years) has elapsed?

math
The half-life of 234U, uranium-234, is 2.52 multiplied by 105 yr. If 98.7% of the uranium in the original sample is present, what length of time (to the nearest thousand years) has elapsed? yr

uncc
the half-life of 234U, uranium-234, is 2.52 x 10^5yr. If 98.5% of thee uranium in the original sample is present, what length of time (to the nearest thousand years) has elasped

pre algebra
The half-life of 234U, uranium-234, is 2.52 105 yr. If 98.6% of the uranium in the original sample is present, what length of time (to the nearest thousand years) has elapsed?

ALGEBRA
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? =

Suppose that you are given a 100 gram sample of a radioactive substance with a half-life of 32 days. How many grams will be left after 192 days?

MATH104
he half-life of 234U, uranium-234, is 2.52 multiplied by 105 yr. If 97.5% of the uranium in the original sample is present, what length of time (to the nearest thousand years) has elapsed? yr

chemistry
Strontium-90 decays through the emission of beta particles. It has a half-life of 29 years. How long does it take for 80% of a sample of strontium-90 to decay? Show process of how you got this

college algebra
An isotope of lead, 201Pb, has a half-life of 8.4 hours. How many hours ago was there 40% more of the substance? (Round your answer to one decimal place.) ____hr

physics
The rubidium isotope 87Rb is a β emitter that has a half-life of 4.9 x 1010 y that decays into 87Sr. It is used to determine the age of rocks and fossils. Rocks containing the fossils of early animal have a ratio of 87Sr to 87Rb of 0.004. Assuming that there was no 87Sr ...

physics
• If you use a cart with half the mass, you reach _______final speed. • If you use half the force, you reach ______ final speed. • If you push twice as long, you cover _______ distance during pushing. • If you use a cart with half the mass, you cover_______ distance ...

chemistry
You have a compound that is subject to decay. If you originally started with 80 g of the compound and you ended up with 5 grams 30 days later, what is the half-life of the compound?

abdul kabir
the half life of an element is 5 days. if we have 10gram of the element initially. what is the mass of the element after 5days and 10days

Probablity
The life time of a certain kind of batteries has a mean life of 400 hours and standard deviation as 45 hours. Assuming the distribution of life to be normal, find i) the percentage of batteries with a life time of atleast 470 hours. Ii) Out of 10000 batteries how many ...

Intergrated physics and chemistry
A 52.0-kilogram skateboarder does a trick on a half-pipe. During the trick, he reaches a speed of 8.90 m/s. The radius of the half-pipe ramp is 3.00 meters. What is the minimum centripetal force necessary to keep the skater on the ramp?

physics
the mass density of a mixture of ethyl alcohol and water is 950kg/m^3. is the mixture mostly water, alcohol, or about half and half. What is your reasoning?

Physics
Calculate the maximum height using the initial speed, half-time, and angle. The initial speeed is 18m/s, half time is 1.8, and the angle is 75

math
half of a gallon is a half gallon. half of a half gallon is a quart. half of a quart is a pint. half of a pint is a cup. a cup is what fraction of a quart? Is the answer 1/4?

shakespeare
places in his life can it be where he was born what else conflicts in his life idk women in his life anne hathaway his wife men in his life can it be his fayher and the ppl he owrked with and his publisher children in his life susanna hamnet and judith mistakes he made idk ...

mechanics of materials
The change in length of a steel wire under an applied load can be halved by keeping all other conditions constant but using:which of the following is correct A. a different material having a Young's modulus half that of steel B half the cross sectional area of the steel wire C...

math
If a hen and a half can lay an egg and a half in a day and a half, then how much time is needed for three hens to lay three eggs?

History
What factors shaped the move from colonial, country life to modern, urban life? What was urban city life like during the rise of urbanization? How was it different or similar to modern urban life?

physics
A car moves a distance of 200 km. It covers the first half of the distance at speed 40 km/h and second half of the distance by speed v. The average speed is 48 km/h. Find the value of v

AP Chem ---
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? Please show the calculating so I can learn to do it.

AP Chem ---
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 iron sample? Please show the calculating so I can learn to do it.

mechanics of materials
Select the correct answer.The change in length of a steel wire under an applied load can be halved by keeping all other conditions constant but using: A. A different material having a Young's modulus half that of steel B half the cross sectional area of the steel wire C half ...

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

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.)

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.)

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)

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.

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.

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?

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 ??

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...

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...

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

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

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?

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.

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 ...

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?

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=?

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.

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 ...

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 ...

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 ...

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 ...

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 ...

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 ...

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 ...

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.

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?

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?

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

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.

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.

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?

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?

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.

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.

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...

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 ...

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

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

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?

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?

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?

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!!

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

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