i got your half-life right here!?
926537
The decay is of the form N(t)/N0 = e^-t/h, where h is a constant.  When t = HL (half life time) N(t)/N0 = .5  therefore N(HL)/N0 = .5 = e^-HL/h.  Take the natural log of both sides to get ln(.5) = -HL/h, so h = HL/ln(2).  Therefore the formula for decay is \n\nN(t)/N0 = e^-t*ln(2)/HL\n\nYou want to find tx such that N(t)/N0 = 100/10^6 = 10^-4.  That means 10^-4 = e^-tx*ln(2)/HL.  Again, taking log (base 10) of both sides gives you -4 = log(e^-tx*ln(2)/HL) or[ -tx*ln(2)/HL]*ln(10).  The time tx is then 4*HL*ln(10)/ln(2).  This comes out 74,411years
403012
why is this question in chemistry???\nit's coming out on the 28th, this month
288544
your first question is somewhat political so i am not answering that but your second question ,that's physics so i will answer that.\nthe radioactive elements have this special property called half-life.\ni will use this eg to explain it.\nthink that you have in your hand 1kg of uranium(dont show that to bush)and assuming its half-life to be around  thousand years ,you will find that after 1000years the uranium in your hand will have decayed and only 0.5kg of the total will be left.and it keeps on like that.so it kinda never ends.Hope you understood.
364348
try downloading the half-life dedicated server, under the tools tab.\nMake sure its the the "Source Dedicated Server", because that is used for all the games that use the Source graphics engine.
816220
i died half way through this question!
267332
Answer = 24.444r   How's that!
270031
If you originally had 100 grams of Nitrogen-16, and then after an unknown (x) number of half lives, you have just 12.5 grams, you can find the number of half lives like this,\n\nremaining = original * (1/2)^x\n12.5 = 100*(1/2)^x --> 12.5 / 100 = (1/2)^x, then take the log of both sides,\nlog (12.5/100) = x*log(.5) --> x = log (12.5/100)/log(.5)\n\nx = 3\nSo 3 half lives have taken place in a period of 21.6 seconds, meaning that each half live is 7.2 seconds.\n\n\nWhen I check my answer against the actual half life value for Nitrogen-16, it is within .07 seconds.  I suspect the problem just rounded off the numbers.\nhttp://www.webelements.com/webelements/elements/text/N/radio.html
303962
Did you get my answer yet?
58155
a comment, and best answer [aghhaam]!
857718
Like the others said...electron.
551575
I thought I just answered this??!!
841559
5.3 seconds from now! Holy cow!
393448
half-life is how long an item remains radioactive and has nothing to do with the lifespan of that item.
1160981
short of total nuclear annihilation--dream on
940898
How much do you owe me?\n\nRemit it immediately!
121876
Plasma, that's how you get nuclear reaction!
176116
A halflife is a form of time constant for characterizing exponential trends with a decay rate of 1/2. Another common time constant decay rate is 1/e.