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# Physics Questions (Moved from Gen. Chat - THINK Campaign) watch

1. II am stuck on a couple of questions on product design and physics and if there is anyone out there to lend me a hand then please by all means do
there isnt anyone available in the academic part at present

anyone have any suggestions?
2. Yes - put up a better, more explanatory title and put the thread in the appropriate subforum.
3. What are your physics questions?
II am stuck on a couple of questions on product <a href="http://www.ntsearch.com/search.php?q=design&v=55">design </a> and physics and if there is anyone out there to lend me a hand then please by all means do
there isnt anyone available in the academic part at present

anyone have any suggestions?
sup.... post the physics question here and i'll do my best .... or PM me
5. blimey quick replies

here is the physics question

Living plants absorb carbon dioxide from the atmosphere, a small quantity of which contains 14
C
6
The Beta Minus Activity A0 ( little 0 ) from a living plant remains constant but once the plant dies, the activity decays according to the expression

A = AoE - lambda/t

where A is the activity at time t.

Calculate

i) the decay constant for Lamba for Carbon ( 14c6 )

ii) the quantity f = the activity after 40,000 years
----------------------------
the intial activity Ao

iii) For objects over 40,000 years old, the carbon 14 beta minus emission becomes indistiguishable fom the background count. Explain the implications of this statement, making clear meaning of the term background count
blimey quick replies

here is the physics question

Living plants absorb carbon dioxide from the atmosphere, a small quantity of which contains 14
C
6
The Beta Minus Activity A0 ( little 0 ) from a living plant remains constant but once the plant dies, the activity decays according to the expression

A = AoE - lambda/t

where A is the activity at <a href="http://www.ntsearch.com/search.php?q=time&v=55">time</a> t.

Calculate

i) the decay constant for Lamba for Carbon ( 14c6 )

ii) the quantity f = the activity after 40,000 years
----------------------------
the intial activity Ao

iii) For objects over 40,000 years old, the carbon 14 beta minus emission becomes indistiguishable fom the background count. Explain the implications of this statement, making clear meaning of the term background count
hi hold on gota get calcy

k

for part i) um id have used Labda X T = 0.693

then lambda = 0.693/5700 = 1.2 x 10-4

ii ) take half lives: 40,000 / 5700 = 7.02 T giving 1 / 128 = 7.8 X 10 -3

d) the background count is jst the random radioactivity, or count detected from the surroundings
and the countrate is so low that no pattern of decay can be seen
7. anyone feel free to check but i'm pretty sure im right cuz ive been reading up on the stuff in detail about radioactivity for the unifying concepts

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