Activity Definition and 193 Threads

Hi. New here (Again). I'm having trouble with solving transient equilibrium problem e-0.0495t= 0.0289 (e-0.0495t- e-0.0289t) _____________ 0.0289-0.0495 I know the answer but can't seem to make this work. Maybe I'm messing up my order of op.

Hello! I just want to humbly ask how do scientists and agencies like NASA, ESA, etc. monitor the activity of our Sun? For example, if Solar storms are occurring in the Sun, how do we know it from Earth? And another specific question: We know that in about 5 billion years (is this...

Mg 2+ (aq) +2 OH- (aq)= Mg (OH)2 (s) If I measure pH of springs near Jenner to be pH=9.5, what can you tell about the equilibrium activity (concentration) of magnesium in that solution? You need to calculate the dissociation constant of water. Not sure how to start this? Any help

One of the things that is supposedly possibly happening as a 2012 disaster is solar activity like flares or coronal mass ejections. This is a good possibility even if it's all hysteria. These events can supposedly theoretically take out electronics. If this happened we would be hurting because...

I'm doing a university project in Sweden where i want to continuously measure the activity in the Bulbospongiosus muscle. Is there any cheap easy method/instrument for doing this or do i need expensive professional medical equipment for this? The main problem i see is how to isolate the...

Homework Statement Hi there, I wanted to use TLD badges for my experiment using cf-252 instead of chips because they were the ones available. I was informed by the Laboratory section that the TLD had a max absorbed dose of 10 Gray. The neutron source cf-252 has an activity of 50...

Lately, I've had roughly a dozen scvhost.exe's running at the same time on my computer. That seems quite high, even after reading up on what scvhost does. Is this normal, or could it be problematic (or a symptom of a problem)? Another issue is that one of the scvhosts usually has much more...

I have been searching online trying to find information about any unusual/unexpected seismic activity on the east coast of U.S. before the earthquake struck on August 23rd. So far, I've not been able to find any articles about that subject. Has anyone seen any information on that topic...

Hello! Peculiar question. I was hoping that someone, probably with a background in development or neuroscience, could answer this question for me: The contraction of heart muscles is achievable independently of any 'outside' source because the heart muscles can initiate action potentials...

Homework Statement I am supposed to calculate the original activity of a radioactive from the following data: Total counts N Measurement time t Since the half-life is short compared to the measure time i can't just divide the counts with the time passed. I really have no clue on how...

What does "Activity" mean in terms of radioactive decay? I came across this term "activity" in text regarding radioactive decay and half lives. It is defined as "number of nuclei in a sample that decay within a given time." That definition if fine but then when presented in a graph life...

can someone explain to me the relationship between enzyme activity and rate of reaction?

Homework Statement A certain artifact is found to have a carbon-14 activity of 0.12 Bq per gram of carbon. What is the age of the object? Homework Equations A = A(initial) * (1/2)^(t/h) where A = current amount A(initial) = initial amount t = time h = half-life (aka half-time) The Attempt...

http://photoblog.msnbc.msn.com/_news/2011/03/12/6256280-how-the-quake-shifted-japan?chromedomain=cosmiclog I thought this was pretty fascinating. According to this, the Earth's rotation has increased in speed as well, by 1.8 microseconds.

Homework Statement The sample is placed 0.12 m beneath a Geiger counter. The counter registers 2 counts per second. What is the activity of the sample?Homework Equations The Attempt at a Solution Just a guess. I am making up formulas here so please tell me if they're not even true. (2...

Which of the following materials have activity Optical ? i know it must have an Chiral molecule,but still i am not know in this list who have it. thanks for help.

Hi everyone, I am currently trying to recognize different activities such as walking, sitting and falling, using a watch which features a 3 axis accelerometer. Currently I have performed 1 minute tests of each activity 20 times but I am struggling on what to do with the data. Does anyone...

Homework Statement The sugar concentration in a solution (e.g., in a urine specimen) can be measured conveniently by using the optical activity of sugar and other asymmetric molecules. In general, an optically active molecule, like sugar, will rotate the plane of polarization through an angle...

Here's some strange stuff coming from Penrose... An article on Universe Today: http://www.universetoday.com/79750/penrose-wmap-shows-evidence-of-%E2%80%98activity%E2%80%99-before-big-bang/ And the paper: http://arxiv.org/abs/1011.3706 Okaaaay... Granted, I need to actually pore over...

I request you all to perform this activity now (it will take less than a minute)- 1)Take a rectangular piece of paper. 2)Make two holes of the size or your fore-finger in it - equidistant from the edges (refer the figure attached. 3)Insert the fore-fingers of your two hands in the holes...

I am meant to deduce the half life from this table (as attached.) I was under the impression that the half life would occur when the initial activity was halved but my answer of 2.34 minutes (from halving the initial activity of 36506) is wrong. Instead, the answer the textbook got was 1 minute...

I did an experiment and i AM A FIRST YEAR STUDENT AND I NEED HELP EXPLAINING WHAT TOOK PLACE. I ADDED 1% STARCH TO THREE TEST TUBES AND THEN 1 DROP IODINE. THEN IN ONE THE TUBE I ADDED 3 DROPS OF 1M NaCl AND then to another i added 3 drops 1M HCl and then i added to the last one i added 3 drops...

The question is that the human body contains 0.2% potassium by weight and the natural abundance of 40K is 0.0118%. The half life of 40K is 1.28x10^9 years and I have to calculate the activity in an adult weighing 75 kg. What I tried was to find the decay constant by 0.693/1.12x10^13 hours =...

I watched this activity on T.V. and performed it: I placed a beaker containing water on the pan of a balance and dipped a stick into the water without touching the wall or bottom of the beaker and observed that the reading of the spring balance decreased. I could not figure out why this...

Homework Statement A student purified cox-2. The crude extract contained 12 g of protein and had 23,000 units of cox-2 activity in 800 mL. The final purification using an affinity column resulted in 3 mL that was 2,300 fold pure. What was the activity of 5 microL of the final purification...

what has "radio" got to do with this activity? Probably sounds silly, but what has "radio" got to do with this activity? I don't know if I'm interpreting this guy's formula right (http://www.hps.org/publicinformation/ate/q8270.html) so can someone confirm this expression for half life: A=...

Homework Statement A sample of processed waste from a nuclear reactor contains 1.0*10^24 plutonium-239 atoms. The half life of plutonium-239 is 2.41*10^4 years. a) How many plutonium-239 atoms will decay in the next 2.41*10^4 years? b) Estimate the activity of the original sample...

Hi! I have this assignment due in Matlab, and I just have no idea how to implement the model in MATLAB ... My main issue at this point is that after I have defined a 50X50 grid to hold the state of each region (where the state can be 0,1,2 or 3 and depends on things like time elapsed in the...

Homework Statement Hi, The question itself doesn't sound too complicated i some-how got the asnwer,just wondering if its correct or not. Question is:A radioactuve isotope wuith a half-life of 1.6x10^5 s disintegrates to form a stable product.A pure sample of 'x' is prepared with an...

Homework Statement What mass of Na2 SO4 has an activity of 10.0 mCi? Sulfur-38 has an atomic mass of 38.0 and a half life of 2.87h Homework Equations Half life= 0.693/ k Rate= kN The Attempt at a Solution I'm not sure where to begin the sulfur-38 part is throwing me off All I...

Hello. I am taking Neculear Power Resource Engineering 402. The one of the homework is to calculate activity of 1g of radium 226 as Becquerel and Curie unit? Can you guys give an equation to me? Thanks.

Hi guys i'm having much difficulties in understanding the relations between half life, decay constant and activity. I'll explain what i known here. T^{\frac{1}{2}} is the half life which is the time to reduce the nuclides by half. \lambda is the decay constant which can be solved...

Hi guys and gals, I am looking for some free software that would allow me to capture what I am doing on my screen in a video format. Much like a screenshot captures a still shot of a particular screen, I would like to take a video. I have no budget for this so I was hoping it there was...

Homework Statement A patient with thyroid problems has radioactive iodine 123 deposited in his thyroid gland. If the iodine has an initial activity of 2.5 MBq, what is its activity after 24 days? Homework Equations A(t)= Ao e^ -(ln(2)/half-life)*t The Attempt at a Solution not...

I just noticed that Li is higher on the activity series than K, which is higher than Na. I thought that the activity series was related to the reactions between the group I metals and water, but the series doesn't correspond with the energy produced by the reactions. I'm definitely missing...

Homework Statement Consider harvesting a radioactive daughter product from a radioactive parent at regular intervals of time, \theta. If n samples of accumulated daughter product are removed at time \theta, 2\theta, ..., n\theta, show that the sum of their residual activities at time n\theta is...

I've always wondered how enzymes could tell the difference between too much substrate and too little substrate to initiate allosteric activities, my teacher tells me that its kinda like collision theory in chemical bonding. That would make sense because if there's too much product, then some of...

I'm trying to find the activity coefficients of benzene and water in the liquid phase, they are in a solution of composition 20 and 80mol% which is beginning to form ice crystals. I know I need to use the 1 parameter margules activity coefficient model i.e. ln (gamma) = A x^2 and I have...

Homework Statement The initial activity of I_131 is 0.74MBq. The half time of I_131 is 8 days. How large is the activity after two days?Homework Equations A = A_0 e^{-\lambda t} The Attempt at a Solution We know t = 2 days A_0 = 0.74 MBq T_0.5 = 8 days 1. Solve the activity constant...

Alaskans brace for Redoubt Volcano eruption http://news.yahoo.com/s/ap/20090130/ap_on_re_us/alaska_volcano The Alaskan and Cascade volcanos tend to erupt with ash, and in some cases, e.g. Mt. St. Helens, explode or rupture. http://www.avo.alaska.edu/activity/Redoubt.php...

In a urine sample (Relman JCI 1961) urine is analyzed. We have a [Na] of 132 mmol/l, K of 62.7 mmol/l, Cl of 182 mmol/l, sulfate of 21.2 mmol/l and some other minor species. The ionic strenght is about 0.22 - now I need to compute the Na+K-Cl-2*SO4. So the ionic strength is higher than 0.1, but...

A http://www.cdejager.com/wp-content/uploads/2008/11/solaractivandclimate-nethjgeosci.pdf of eminence grise Cees de Jager. If you think it's too old, check that Silvia Duhau and Dirk Callebaut are credited for their support. Anyway in the abstract:

One isotope (X) contains an equal number of protons and neutrons. Another isotope (Y) of the same element has twice the number of neutrons as the first isotope does. Determine the ratio rY/rX of the nuclear radii of the isotopes.

The sugar concentration in a solution can be measured conveniently by using the optical activity of sugar nad other asymmetric molecules. In general, an optically active molecule like sugar will rotate the plane of polarization through an angle that is proportional to the thickness of the sample...

Didn't really have any idea when I started to write the problem, but I think I've managed to work it out now posting for clarification. Homework Statement Estimate the time it will take to produce a 100 μCi source of 36Cl by irradiating 1g of natural nickel chloride (molecular weight 129.6)...

we seem to be suffering from strange, what I am pretty sure, is electrical activity in our house. We seem to be getting electrical charges through bed mattresses, that actually make the mattress feel as if it is moving and/or strange extreme heating up of the bed mattresses. Also, when we are...

Help! calculating the the activity of a radioactive sample! 1. find activity R 2. the average 70 KF males contain 140 gram of potassium. of this 0.012% is potassium 40. the half life of potassium 40 is 1.2 billion years. so how many K40 decay per second and what is the activity of K40 in...

I have a few emotion questions and how it effect the brain I'm know little of physics or medicine I'm doing research on affirmations. John does positive affirmations john reads a self help book and visualises and repeats; I'm rich and successful many times. He does this for 30...

I know that it's likely impossible to predict exactly when an earthquake will strike or when a volcano will erupt, but I was just wondering what technologies existed out there to at least forecast them and let people know that something is imminent. Again, could remote or wireless sensing...

The element rubidium consists of two isotopes; the stable Rb-85 and the radioactive Rb-87 (abundance 27.83%). What is the specific activity of natural rubidium chloride? if you use A(r)=85.47 g.mol-1 for Rb-element, A(r)= 86.91 g.mol-1 for Rb-87, and M(r) = 120.92 g.mol-1 for RbCl.