V1003 Science & Society Homework #1
Due Sept. 27, 2010 in class
As with all homework assignments, the work must be your own.
I. Population and Demographic Transitions
1. Showing your calculations, calculate the population growth rates for the following countries and time intervals:
a. Uganda: 7,470,000 (1960) to 57,900,000 (2004)
b. Sweden: 7,480,000 (1960) to 8,960,000 (2004)
c. Pakistan: 45,850,000 (1960) to 152,060,000 (2004)
d. China: 667,070,000 (1960) to 1,296,000,000 (2004)
N = Noexp(rt)
R=(ln(N/No))/t
a. 8.5%
b. 0.75%
c. 5.0%
d. 2.8%
2. Using the “Rule of 70” estimate the year from now when the population will double for each country in Question 3 based on the average growth rate you calculated.
a. 8.2 years
b. 93 years
c. 14 years
d. 25 years
3. Using the modern global 1.3% population growth rate, what would the global population be in 2060, and why won’t this happen? (Show calculations).
N = Noexp(rt)
12.8 billion, because the developing world demographics are shifting toward lower fertility rates.
4. Afghanistan, Yemen, South Korea, and Sweden present three very different demographic histories that illustrate the various stages of development for different countries. Using the GapMinder software on your favorite browser (http://tools.google.com/gapminder/), let’s inspect some of the major demographic trends that distinguish each country.
a. Change the x-axis (horizontal) to “time” and the y-axis to “life expectancy”. Select Afghanistan, Yemen, South Korea, and Sweden from the right hand country list. Sweden has the longest demographic records in the world and so they provide a useful longer history to compare to other countries. Then hit the “play” button on the lower left side (may need to do it twice).
In one sentence per country, comment on the life expectancy trends for each country. How do the trends compare?
Sweden is highest, ties with S. Korea (but S. Korea only got there very recently). Yemen experienced a dramatic increase in life expectancy. Afghanistan still has very low life expectancy.
b. Now change the y-axis (vertical) from “life expectancy” to “children per woman (fertility)” and press the play button again.
In a few lines, comment on the demographic transition stage for each country based on the lecture notes on this topic. When did each country pass through Stages 2-3 transition?
Sweden: Entered Stage 3 before 1950
S. Korea: Entered Stage 3 in 1970
Yemen: Entered Stage 3 in 1989,
Afghanistan entered Stage 3 in 1995
c. try changing the x-axis from “time” to other variables that are well correlated with “Children per woman (fertility)”. Identify these two different variables and provide a one sentence description of why you think this variable is so important to determining Fertility rates.
Education, Child mortality rate, female literacy rate,
Income per person is an effect, not a cause (can’t buy health, see below)
5. Now, pick any two countries of your choosing by checking them on the right-side list. (remove China, India, and US from the checked list). Change the x-axis to “Income per capita” and change the y-axis to “child mortality” and press “Run”. Also examine the y-axis data for these countries for “child mortality”, “fertility”, and “life expectancy”.
a. In one short paragraph please, compare and contrast their demographic evolution over the 1975-2004 period. Specifically, address when the major demographic changes took place and what happened in terms of child fertility and mortality trends.
b. Do you know of any specific socioeconomic events in each country that underlie the observed changes ? (you can research this online).
c. In what demographic stage would you place each country and why?
6. Many African countries have not participated in the recent, widespread demographic shift over past decades, when many once-developing countries shifted to a wealthy, developed-nation status. Using three countries - Sweden, Korea, and Zimbabwe – explore the impact of the HIV/AIDS crisis on populations, development, and future growth.
Make the following three plots (using the “trace” feature to show the time evolution of these countries from 1950-2007):
a) income (x-axis) versus life expectancy (y-axis)
b) income (x-axis) vs. children per woman (fertility, y-axis)
II. Radiation and Ozone
7. How would the vertical profile of the atmospheric temperature differ from the currently observed one if we removed all of the ozone? Sketch the vertical profiles of temperature for the atmosphere with and without ozone. Explain.
Absorption of UV radiation by ozone warms the stratosphere and produces its increase in temperature with height. The mesosphere is kept warm by conduction of heat from the stratosphere. If ozone were removed, the heating in the stratosphere would not occur, and neither would the heating of the thermosphere, so we could expect temperature to decrease or remain constant with height in both layers.
a) b)
c) Why does the Earth mainly radiate energy at longer wavelengths that the sun? (2-3 lines).
Both the Earth and the Sun behave as blackbodies. Wien’s law for blackbodies says that the higher their temperature, the shorter the wavelength at which they will radiate the most. Therefore, since the Earth is colder than the Sun, it will radiate at longer wavelengths.
8. For each of the following indicate which has the higher temperature. Explain your reasoning and support your answer with arguments based on what was discussed in class (2 lines).
a) A distant blue star (for example Rigel in the Orion constellation, left) or a Red Giant star (right)?
The blue supergiant has a higher temperature. We know this from Wien’s law for blackbody radiation. Wien’s law tells us that the temperature of a blackbody is inversely proportional to its wavelength of maximum emission. A higher temperature indicates that the peak emission is at shorter wavelengths.
The wavelength of blue light is shorter than the wavelength of yellow light, so the temperature emitted by the blue star (Rigel) will be higher than the temperature emitted by the red star.
b) A red hot metal bar or a yellow birthday candle flame?
The wavelength of yellow light is shorter than the wavelength of red light, so the temperature emitted by the yellow flame will be higher than the temperature emitted by the red bar. We know this by Wien’s law.