Please show all clear steps, thank you.
Ex. Suppose an element X has a half-life of 20 weeks.
a) Express the percent remaining P as a function of the number of half lives elapsed, n.
b) What percent of element X remains after:
(i) 90 weeks
(ii) 50 weeks
(iii) 200 days
(iv) 2 year
c) If a sample of element X weighs 50g, what is the weight of element X after 100 days?
Thank you so much :)
幫忙Exponential Growth & Decay
2015-02-06 10:57 pm
回答 (4)
2015-02-08 7:42 am
✔ 最佳答案
(a) P = (1/2)^n where n is number of half lives elapsed(b)(i) 90 weeks => n = 4.5So, P = (1/2)^4.5 = 4.4194%(ii) 90 weeks => n = 2.5P = (1/2)^2.5 = 17.6777%(iii) 200 days => n = 1.42857P = (1/2)^1.42857 = 37.1499%(iv) 2 year => n = (2 * 52)/20 = 5.2P = (1/2)^5.2 = 2.7205%(c) 100 days => n = 100/140 = 0.714286The weight of element X after 100 days = 50 * (1/2)^0.714286 = 30.4753g
2015-02-07 4:08 pm
泉路，
點解你問返我轉頭嘅？
點解你問返我轉頭嘅？
2015-02-07 9:22 am
Think P = 0.5 when n = 1, P = 0.25 when n = 2, it is easy to come up with this formula.
(a) P = (0.5)^n
(b) n = t/20, so P = (0.5)^(t/20), we have
(i) 4.42%
(ii) 17.68%
(iii) 37.15%
(iv) 2.69%
Numbers accurate to two decimal places.
(c) Using the formula above, at the 100th day, 60.95% of the element is still there, so 30.48g remains.
(a) P = (0.5)^n
(b) n = t/20, so P = (0.5)^(t/20), we have
(i) 4.42%
(ii) 17.68%
(iii) 37.15%
(iv) 2.69%
Numbers accurate to two decimal places.
(c) Using the formula above, at the 100th day, 60.95% of the element is still there, so 30.48g remains.
2015-02-07 5:03 am
This problem has problem?
Half life should be integer?
Half life should be integer?
收錄日期: 2021-04-15 18:12:58
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