Tuesday

July 22, 2014

July 22, 2014

Number of results: 29,221

**physis**

Search: 2. Explain how radioactive decay has always warmed the Earth from the inside, and nuclear fusion has always warmed Earth from the outside.
*January 26, 2014 by barbara*

**Physics**

Explain how redioactive decay has always warmed the Earth from the inside and how nuclear fusion has always warmed the Earth from the outside.
*April 25, 2008 by Rob*

**Science- Radioactive Dating**

Which of the following statements about radioactive dating is true? a. Radioactive decay is the rate at which new atoms form. b. During radioactive decay, atoms break down, releasing particles or energy. c. The rate of decay of a radioactive element cannot be approximated. d. ...
*October 10, 2013 by Anonymous*

**earth science**

how does radioactive decay provide heat energy within the earth
*July 19, 2008 by kate*

**calculus**

Carbon-14 is a radioactive substance produced in the Earth's atmosphere and then absorbed by plants and animals on the surface of the earth. It has a half-life (the time it takes for half the amount of a sample to decay) of approximately 5730 years. Using this known piece of ...
*July 24, 2009 by j*

**Physics **

Hi Radioactive decay - A radioactive nuclide has a decay constant of - 10^-6 s-1 what is its half life ? I have come up with is IN (2) / 0.000001 s-1 = 693147.18055 which iam having troube working into real figures Can anyone help please .. thanks
*August 24, 2013 by Freddo*

**Physics ... **

Hi Radioactive decay - A radioactive nuclide has a decay constant of - 10^-6 s-1 what is its half life ? I have come up with is IN (2) / 0.000001 s-1 = 693147.18055 which iam having troube working into real figures Can anyone help please .. thanks
*August 24, 2013 by Freddo*

**earth**

3. What can scientists learn from the rate at which radioactive elements decay?
*December 10, 2013 by Elizabeth*

**science**

Which statement best explains why dating geologic materials from the Quarternary Period uses a different radioactive isotope than for materials from the cambrian Period? a. all rocks contain radioactive substances. b. some isotopes decay faster than others. c. not all isotopes...
*April 4, 2009 by Angie*

**8th Grade Earth Science Help?**

Which of the following terms refers to the time it takes for one-half of the radioactive atoms in a sample of a radioactive element to decay? - relative age - absolute age - potassium-argon data - half-life** Is my answer correct?
*January 14, 2014 by Rainshine*

**Chemistry**

How many half lives will it take for a sample of a radioactive isotope containing 20000 radioactive nuclei to decay to 2000 radioactive nuclei
*November 16, 2010 by Dianne*

**Earth Science**

1. Is it true that since energy cannot be created nor destroyed, the total energy of the river system remains constant? 2. What is the source of energy that powers the water cycle? a. sunlight insolation b. kinetic energy c. radioactive decay d. gravitational potential energy ...
*November 24, 2008 by John*

**Differential Equations**

Model radioactive decay using the notation t = time (independent variable) r(t) = amount of particular radioactive isotope present at time t (dependent variable) -λ = decay rate (parameter) Note that the minus sign is used so that λ > 0 a) Using this notation, ...
*January 17, 2013 by Quinn*

**radioactive decay**

What elements results if one of the neutrons is in a nitrogen neucleus is converted by radioactive decay into a proton? The atomic number goes from 7 to 8, while the atomic weight stays the same. An electron (beta-) is emitted from the nucleus. Actually, this process does not ...
*June 28, 2005 by Jarrad Schomaker*

**Math - D.E.Q.**

The half-life of a radioactive isotope is the amount of time it takes for a quantity of radioactive material to decay to one-half of its original amount. i) The half-life of Carbon 14 (C-14) is 5230 years. Determine the decay-rate parameter for C − 14.
*January 18, 2011 by Justin*

**MATH!**

The mass of a radioactive substance follows an exponential decay model, with a decay rate of 5% per day. A sample of this radioactive substance was taken six days ago. If the sample has a mass of 3 kg today, find the initial mass of the sample. Round your answer to two decimal...
*March 15, 2012 by Kim*

**science**

A 10g sample of radioactive substances is lift to decay for five half-lives. How much of the radioactive substance remains?
*February 19, 2013 by mirian hernandez*

**chemistry -- radioactive decay **

suppose you have a 150 gram sample of radioactive decay god-191 which has a half- life of 3.4 hours. how many grams of gold will ramain after 10hrs ? after 24 hrs? answer : 10 hrs :10/3.4= 2.94 times 150*(1/2)^2.94 = 18.75 grams 24 hrs: 24/3.4 = 7.06 150*(1/2)^7.06= 1.12 right...
*September 18, 2012 by Maria*

**Science- Earth and its History**

What can scientists learn from the rate at which radioactive elements decay? A. a rock's absolute age* B. the relative age of rock layers C. where one soil horizon ends and the next begins D. the difference between molds and casts. After six half-lives, what percentage of a ...
*October 15, 2013 by Anonymous*

**Algebra**

What are some real-life examples of exponential decay? Please help me think of some ideas...except radioactive decay.
*January 30, 2014 by Anonymous*

**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*

**physics**

if 5/6th of a radioactive sample decay in 70 years and 1/6th remain. how can you find the half life without knowing the decay constant can you help?
*May 21, 2008 by ronny*

**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 *

**mathematics**

what is the equation for exponetial decay(radioactive decay) and how to use the half life in the equation
*November 2, 2011 by anonymous*

**Science [Earth]**

Can you please: 1. briefly explain the concept of radioactive decay and describe how it can be used to find the absolute age of rocks. 2. contrast relative age with absolute age and describe at least three methods of determining either. 3. compare advantages and disadvantages ...
*May 8, 2009 by xxx*

**science**

during radioactive decay atoms of a radioactive element break down and change into other atoms of another element-all at once a) true b) false
*December 11, 2013 by victoria*

**Math-Exponential Decay**

A lab technician had 58 grams of a radioactive substance. Ten days later, only 52 grams remained. Find the half-life of the radioactive substance.
*May 12, 2014 by Anonymous*

**chemistry**

How long will it take for 25% of the C-14 atoms in a sample of C-14 to decay? The half-life for the radioactive decay of C-14 is 5730 years. If a sample of C-14 initially contains 1.1 mmol of C-14 , how many millimoles will be left after 2275 years?
*February 28, 2010 by Anonymous*

**Science**

What can scientists learn from the rate at which radioactive elements decay? A. a rock's absolute age* B. the relative age of rock layers C. where one soil horizon ends and the next begins D. the difference between molds and casts. After six half-lives, what percentage of a ...
*October 15, 2013 by Anonymous*

**Science**

What can scientists learn from the rate at which radioactive elements decay? A. a rock's absolute age* B. the relative age of rock layers C. where one soil horizon ends and the next begins D. the difference between molds and casts. After six half-lives, what percentage of a ...
*October 16, 2013 by Anonymous*

**Science**

What can scientists learn from the rate at which radioactive elements decay? A. a rock's absolute age* B. the relative age of rock layers C. where one soil horizon ends and the next begins D. the difference between molds and casts. After six half-lives, what percentage of a ...
*October 16, 2013 by Anonymous*

**Calculus-Modeling Equations**

An unknown radioactive element decays into non-radioactive substances. In 420 days the radioactivity of a sample decreases by 39 percent. 1.What is the half-life of the element? 2.How long will it take for a sample of 100 mg to decay to 46 mg?
*March 6, 2009 by Kim*

**chemistry**

A particular radioactive substance has a half-life of 4 minutes. How long will it take for 250 g of this radioactive material to decay to less than 0.1g? 24 min 36 min 40 min 48 min 72 min I got 32 min but that not one of the choices. Please help
*December 5, 2011 by Anonymous*

**algebra **

Scientists can determine the age of ancient objects by a method called radio carbon dating. The bombardment of the upper atmosphere by cosmic rays converts nitrogen to a radioactive isotope 14C of carbon with a half-life of about 5710 years. Vegetation absorbs carbon dioxide ...
*March 7, 2013 by Emily*

**Chemistry**

Pu-238 is radioactive by alpha-decay (half-life 87.7 y). Each decay releases 5.6 MeV of energy. Pu-238 is sometimes used to power space probes. If all the decay energy can be converted to electric power, what mass of Pu-238 would be required to power a 22 kW space probe for at...
*October 15, 2013 by Jane*

**chem**

Pu-238 is radioactive by alpha-decay (half-life 87.7 y). Each decay releases 5.6 MeV of energy. Pu-238 is sometimes used to power space probes. If all the decay energy can be converted to electric power, what mass of Pu-238 would be required to power a 22 kW space probe for at...
*October 16, 2013 by Jane*

**science**

Calculate the uranium ratios in the natural uranium decay chain using radioactive decay relationships. Compare to the value obtained using published natural abundances.
*January 29, 2011 by Anonymous*

**Algebra 2 help...**

A half life of a certain radioactive is 36 days. An initial amount of the material has a mass of 487 kg. Write an exponential function that models the decay of this material. Find how much radioactive material remains after 5 days. Round your answer to the nearest thousandth.
*January 10, 2014 by Maria *

**Algebra**

A defective nuclear reactor is leaking radioactive iodine-131. The rate of decay of iodine-131is given by the function defined by A(t)=A_0 e^(-0.087t), where t is time in days. How long will it take any quantity of iodine-131 to decay to 25% of its initial amount?
*June 19, 2013 by AZ*

**chemistry**

Write a partial decay series for Po-214 undergoing the following sequential decays: á, â, á, â. Use e for an electron. Use the format +1 or -1 for charge. a)a decay b)â decay c)a decay d)â decay
*September 30, 2010 by lisa*

**Math**

A radioactive substance decays according to the formula Q(t) = Q0e−kt where Q(t) denotes the amount of the substance present at time t (measured in years), Q0 denotes the amount of the substance present initially, and k (a positive constant) is the decay constant. (a) ...
*April 5, 2014 by Vanessa*

**Math**

A radioactive substance decays according to the formula Q(t) = Q0e−kt where Q(t) denotes the amount of the substance present at time t (measured in years), Q0 denotes the amount of the substance present initially, and k (a positive constant) is the decay constant. (a) ...
*April 6, 2014 by Vanessa*

**science**

describe how radioactive isotopes decay
*December 5, 2010 by kayla*

**Physical Science**

What is an example of radioactive decay?
*October 13, 2011 by Brooke*

**phys **

Although most natural potassium nuclei are stable 39K (93.3%) or 41K (6.7%) nuclei, about 0.0117% are radioactive 40K nuclei, which have a half-life of 1.26 billion years. What fraction of all the potassium nuclei in your body will undergo radioactive decay in the next 1.04-...
*June 6, 2013 by Anonymous*

**chem**

Complete the following radioactive decay problem. 234 4 U ---> He+ 92 2 how do i do this?
*May 20, 2011 by Alie*

**Science**

How is nuclear radiation produced? What are 3 types of radioactive decay and how do they work? Thanks!
*April 24, 2009 by Lauren*

**Science**

Need help with constructing a model of radioactive decay with popcorn kernals
*March 20, 2011 by Kim*

**Science**

3. What can scientists learn from the rate at which radioactive elements decay? (1 point)
*November 6, 2013 by Nicole*

**Science**

3. What can scientists learn from the rate at which radioactive elements decay? (1 point)
*November 6, 2013 by Nicole*

**chemistry**

You want to heat a satellite by radioactive decay of 238 plutonium. Assume you need heating of 200 Watts (J/s), how many Becquerel you need in your plutonium sample, if the decay energy of 238 plutonium is 5.593 MeV? (1 joule = 6.24 x 10^18 eV ) When will 1 mg of Pu be ...
*November 19, 2010 by Anonymous*

**chem**

Write a partial decay series for Rn-220 undergoing the following sequential decays: á (alpha decay), á, â(beta decay), á. (Enter the mass number in the first raised box, the atomic number in the second lower box and the symbol of the element in the third box. Enter the nuclide...
*September 30, 2010 by lisa*

**math**

An unknown radioactive element decays into non-radioactive substances. In 100 days the radioactivity of a sample decreases by 64 percent. a)(a) What is the half-life of the element? half-life: b)How long will it take for a sample of 100 mg to decay to 51 mg? time needed:
*May 18, 2013 by Rachel*

**Problem**

If an Elements has a half life of 20mins what is the radioactive decay of a 200gram sample?
*June 11, 2013 by Half life*

**physics**

The furthest distance from the Sun to Earth is df=1.521E8 The shortest distance from the Sun to Earth is ds=1.47E8 To simplify the problem, assume that the Earth's axis is always perpendicular to the plane of its trajectory around the Sun. The Sun always shines on half of the ...
*June 9, 2013 by rishabh*

**Science**

Radioactive substance decays so that after t years, the amount remaining, expressed as a percent of the original amount, is A(t)=100(1.6)^(-t). a) Determine the function A’, which represent the rate of decay of the substance. b) what is the half-life for this substance? c) ...
*March 6, 2012 by jessica*

**Geology**

If the decay constant for radioactive decay of ^40 K is λ = 5.543*10^(-10) / year, use this equation to calculate ages of the samples in the following table: t(1/2) = 0.693/λ 1)What is the half life of 40K? table -----Np --- Nd---- Nd/Np A)6439-----2303---0.358 B)...
*November 21, 2013 by Maura*

**Earth Science**

Describe how Earth would be different today if. It contained no radioactive material. What would the consequences be for the Earth's interior layer?
*September 30, 2009 by Breanna*

**Earth Science**

Describe how Earth would be different today if it contained no radioactive material. What would the consequences be for the Earth’s interior layers?
*December 2, 2010 by Jack*

**General chemistry**

What is the decay constant for a radioactive isotope which decreases to 34% of its original value in 2.48 hours?
*April 27, 2010 by me*

**Calculus**

[Exponential growth & decay] The half-life of radioactive strontium-90 is approximately 29 years. In 1965, radioactive strontium-90 was released into the atmosphere during testing of nuclear weapons, and was absorbed into people's bones. How many years does it take until only ...
*October 6, 2009 by Z32*

**earth**

how Earth would be different today, if it contained no radioactive material
*November 3, 2009 by Lizeth*

**science**

Predicting Table of radioactive isotopes below Isotope type of decay Uranium-238 Alpha Nickel-63 Beta Iodine-131 Beta Radium-226 Alpha With the help of a periodic table, predict the element that forms in each case. Explain your reasoning.
*May 4, 2014 by Andrean*

**Pre Calculus**

Exponential Growth and Decay Find the half-life of a radioactive substance that decays by 5% in 9 years.
*October 22, 2011 by Josh*

**Science**

Identify and describe the type of radiation emitted during the radioactive decay of the radioisotope xenon 135
*May 21, 2013 by Olivia*

**Geology**

Does this sound right? Describe your assigned method and how it is used to evaluate geologic time. My assigned method was Absolute Dating / Numerical Age. Absolute Dating / Numerical Age is the process that assigns a numerical age ( this tells how old a rock or fossil is);to a...
*March 31, 2009 by A.W.*

**science**

Hello! I need help with some Science things. 1. Where is a good place to find a picture that describes radioactive decay, fussion and fission/ 4. Scientists use the amount of radioactive isotopes found in rocks and fossils to calculate their ages. This process is called_____ 5...
*January 15, 2009 by Amy*

**advanced functions HELP!!!**

Radioactive decay is the process by which an unstable element transforms into different element, typically releasing energy as it does so. For 500g of a radioactive substance with a half-life of 5.2 hours, the amount remaining is given by the formula M(t)=500(0.5) ^ t/5.2 a) ...
*December 10, 2008 by james*

**geology / science**

the age of granite can be determind using radiometric dating, explain the basis for the determination of a 238 U- Pb radiometric date of 1120 Ma for a granite. I have as the answer 238 U decays to Pb with an experimental law, that is the amount of U and Pb in granite are ...
*April 18, 2007 by bex*

** Chemistry - radioactive decay .**

list 2 reason why this isotope of gold- 191 would not be a good substitute for making jewelry?
*September 18, 2012 by Maria*

**Physics**

A radioactive substance decays from 2.0kg to 1.6kg in 156 days. How long would it take to decay to 1.1kg?
*August 7, 2013 by Alice*

**physics**

Explain with diagram the variation of the acceleration due to gravity (g) i) At a height h above the earth surface Inside the earth towards the centre of the earth. ii) What is the value of g at the centre of the earth. 2)Explain with example the term, damped harmonic motion 3...
*July 30, 2008 by GoodMatrix*

**pre-calculus**

Given that the radioactive decay equation is q = 1250 e-0.05t, if t is in months, the amount of milligram present after 4½ year is?
*March 4, 2012 by romain*

**Chem 2**

The half-life for the radioactive decay of U-238 is 4.5 billion years and is independent of initial concentration. a) How long will it take for 10% of the U-238 atoms in a sample of U- 238 to decay? b)If a sample of U-238 initially contained 1.9×1018 atoms when the universe ...
*July 21, 2011 by Kristina*

**Science**

What process involves the comparison of rock layers with others in a sequence to determine its age? radioactive decay radiometric dating relative dating absolute dating To determine the most accurate and precise age of Earth's oldest rocks, geologists would use relative dating...
*October 30, 2013 by Abby*

**Calculuc**

How do you set up this problem? The decay constant for the radioactive element cesium 137 is .023 when time is measured in years. Find its half-life.
*August 22, 2012 by Jillian*

**Astronomy**

I have another question. What would an observer on the Moon looking at the Earth see? a) always see a fully-illuminated Earth b) always see a half-illuminated Earth c0 see phases of Earth d) see continuous darkness These are the four answers, but I would think it would depend ...
*July 30, 2010 by PJ*

**chem**

what changes in atomic number and mass number occur in a positron emmision of radioactive decay?
*June 2, 2008 by jerson*

**math**

A 10 kg quantity of a radioactive isotope decays to 3 kg after 17 years. Find the decay constant of the isotope.
*February 3, 2011 by Eric*

**math**

A 10 kg quantity of a radioactive isotope decays to 3 kg after 17 years. Find the decay constant of the isotope.
*February 3, 2011 by Eric*

**math**

A 10 kg quantity of a radioactive isotope decays to 3 kg after 17 years. Find the decay constant of the isotope.
*February 3, 2011 by Eric*

**math**

A 10 kg quantity of a radioactive isotope decays to 3 kg after 17 years. Find the decay constant of the isotope.
*February 3, 2011 by Eric*

**math**

A 10 kg quantity of a radioactive isotope decays to 3 kg after 17 years. Find the decay constant of the isotope.
*February 3, 2011 by Eric*

**math**

A 10 kg quantity of a radioactive isotope decays to 3 kg after 17 years. Find the decay constant of the isotope.
*February 3, 2011 by Eric*

**math**

A 10 kg quantity of a radioactive isotope decays to 3 kg after 17 years. Find the decay constant of the isotope.
*February 3, 2011 by Eric*

**Physical Science**

The heat of volcanoes and hot springs comes from trace amounts of radioactive minerals found in the Earth's interior. Why isn't the same rock at the Earth's surface warm?
*March 10, 2008 by Rachel*

**Physical Science**

3. Radioactive decay of nuclei often involves several decays before a stable nucleus is formed. This is called a decay chain. What stable isotope is formed when radon-222 undergoes a decay chain of four alpha decays followed by four beta decays? (A) tungsten-206 (B) platinum-...
*November 20, 2013 by Adam*

**chemistry**

a radioactive material is undergoing nuclear decay. After 40 minutes, 25% of the sample remains. What is the half-life of the sample
*August 27, 2011 by marjani*

**Physics**

A radioactive substance decays from 2.0kg to 1.6kg in 156 days. What is the decay constant and the half life of the substance?
*August 6, 2013 by Alice*

**Chemistry**

The nuclide 12 N 7 is unstable. What type of radioactive decay would be expected??? my guess is either gamma or beta. are either of those correct?
*March 4, 2008 by Jonathan*

**math**

The decay of 333 mg of a radioactive substance is given by A(t) = 333e-0.024t, where t is time in years. Find the amount left after 17 years.
*April 8, 2011 by allison*

**science**

I need a picture that describes radioactive decay, fussion and fision. Someone said that they would give me a link earlier but they didnt. Thank you! This website helps me out so much.
*January 15, 2009 by Amy*

**chemistry**

use logic and simple math to determine how long it will take for a sample of potassium- 42 to decay from 8mg to 0.25mg if the half-life of this radioactive isotope is 124 hours
*October 12, 2010 by jay 1*

**Chemistry**

Tc-99 is a radioactive isotope that decays by beta emission and is used by radiologists in the diagnosis of liver disease. Its decay behavior is shown by the activity-time table. What is its half-life?
*December 10, 2011 by Jennifer*

**chemistry**

I am having trouble understanding what the concept is for writing these out. Write a balanced nuclear equation for the alpha decay of each of the following radioactive isotopes: curium-243, 22589Ac
*December 5, 2013 by ellie*

**physics**

Radioactive decay of granite and other rocks in Earth's interior provides sufficient energy to keep the interior molten, to heat lava, and to provide warmth to natural hot springs. This is due to the average release of about 0.03 J per kilogram each year.Find an increase in ...
*April 1, 2012 by christy*

**chemistry**

Help plzzz Besides the major types of radioactive decay, there are two others: positron emission and electron capture. • Compare and contrast positrons with electrons. • Explain how positron emission works and how it causes transmutations. • Explain how electron capture works ...
*May 31, 2013 by Help!!! Maddie*

**math**

if the rate for radioactive decay for a substance is r=-.0063 and time is being measured in days how do you find the half-life of the substance to the nearest hour?
*March 30, 2009 by mike*

**Phyics Toughest question on earth**

Estimate the time difference between the longest day and the shortest day of a year in seconds if you lived on the Earth's equator with the assumptions below. Note: this is not the difference between solstices as we are adjusting the earth's rotation axis to be in the orbital ...
*June 4, 2013 by Mathslover*

**Earth Science**

Earth is always changing. What are two forces that cause the earth's surface to constantly change and what are their effects on the planet? Please answer within a few minutes.
*November 4, 2009 by Elizabeth*

Pages: **1** | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | Next>>