Please show all clearl steps, thank you.
Ex.1 A ball dropped from 30m bounces to 80% of it's original height after each bounce. How high will it be after:
a) the sixth bounce?
b) the 15th bounce?
Ex.2 In 1988, the world population reached 5 billion, and was increasing at the rate of 1.6% per year. If we assume that the rate of growth is constant, what will the population of the earth be in 2005?
Thank you very much ;)
Exponential Growth & Decay： 難！
2015-02-06 11:04 pm
回答 (1)
2015-02-07 12:24 am
✔ 最佳答案
The two questions seem to have no relation to any physics principles. It could be solved by mathematics only.1. The height reached H after n bounces is given by,
H = (30) x (0.8^n) m
Hence, answers to (a) and (b) can be found by substiting n = 6 and 15 respectively.
2. No. of years passed from 1988 to 2005 = 17
Hence, new population = 5 x (1+ 1.6/100)^17 billion = 6.55 billion
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