Suppose you have a sample of potassium feldspar from a rhyolite and you measure the ratio of atoms of 40Ar to 40K of 0.024 to 1, or for every 10000 atoms of 40K you find 240 atoms of 40Ar. For this problem, consider the decline of 40K from an initial value to the measured value.
a. What is Nt?
b. What is the ratio of atoms of radiogenic 40Ca to radiogenic 40Ar?
c. What is the ratio of atoms of radiogenic 40Ca to 40K
d. What is the current daughter:parent ratio ((40Ca+40Ar)/40K)?
e. For every 10000 atoms of 40K in the sample today, how many atoms of radiogenic 40Ca plus 40Ar are there now?
f. For every 10000 atoms of 40K in the sample today, how many atoms of 40K were there in the sample when it formed? This number is No
g. What is the age of the sample?
College Geology Homework - SraJMcGin, Wednesday, October 20, 2010 at 2:25am
Writeacher's lesson on "How to Search on the Internet" should help you find the information you seek:
For Internet searching:
At this webpage, you can go immediately to the search sites (first three columns across the top) -- or even better you can scroll down until you see the section called HOW TO SEARCH THE INTERNET. Those are the links to start with. You'll not only learn how to come up with good search terms, but also how to evaluate the webpages you get as results. Some will be good and others will be garbage. You need to know how to tell the difference.
My favorite way to search is to go to Google's advanced search page http://www.google.com/advanced_search?hl=en and put my search words or phrases into the first or second search box (either "all the words" or "exact phrase").
Learning to use Google or other search engines can save you time and help you learn to find information efficiently. Here are some websites that can teach you how:
... and one to help you judge whether a particular website's information is worth your time: