Name________________________ 1

219: Energy and the EnvironmentExam: March 5, 2015

You have 80 minutes to answer both portions of the test. The test is closed-book, open-note. You may use calculators, but not laptops or smartphones. Please put your name on the top of ALL pages. Answer the questions in the spaces provided. You can go onto the back if necessary.

1) (15 pts) a) Show that the units for kinetic energy [1/2 (mass)(velocity)2] and gravitational energy [(mass)(gravity)(height)] are the same. b) A device called the GravityLight uses gravity to power a small LED light. Suppose that you lift a 10 kg bag of sand 2 meters high. How much energy (in joules) have you given it? c) If you can use this amount of energy to power a small LED light bulb (about the brightness of a small candle) for 30 minutes, what is the approximate wattage of the bulb?

Name________________________ 2

2) (15 pts) a) Suppose that you turn on a forced-air electric heating system in your house so that you can stay warm, and that your electricity comes from a hydroelectric power plant. Describe the sequence of energy and mass conversions involved with the process, start to finish (the finish is you getting warm).b) The efficiency of an individual incandescent light bulb is typically about 5%. Where does the other 95% of the energy go?c) The textbook describes the full process of powering an incandescent light bulb as being 1.3% efficient. Why is this less than 5%? (i.e., where did the rest of the energy go?)

Name________________________ 3

3) (15 points) a) Explain why taking a shower is one of the most expensive things you use energy for in your home.b) Explain why is this related to the reason that you feel cold when you get out of the shower?c) Explain why taking a shower is even more expensive in the wintertime than in the summertime. (Assuming you like to take the same temperature shower.)

Name________________________ 4

4) (20 pts) Examine the diagram of the anticline on the right.a) How did this anticline likely form?b) What can you assume about the layer of rock on top of the region that says “Gas?”c) Why are the water, oil, and gas layered in this way?d) How could you find this region of gas without having to drill into it?e) Sometimes geologic folds like this are accompanied by pre-existing faults from earthquakes. Why might that be risky with certain kinds of hydrocarbon removal methods?

Name________________________ 5

5) (15 points)a) Briefly, why is the spectrum of radiation that is arriving from the sun (“Downgoing Solar Radiation”) centered at a different wavelength than the radiation leaving the earth (“Upgoing Thermal Radiation”)?b) Explain why these two curves (incoming from the sun and leaving from the earth) have different shapes.c) What is the impact on humans of the shaded region at the far left end of the “Oxygen and Ozone” row?

Name________________________ 6

6) (10 pts) One of the challenges of making decisions about energy policy is balancing short-term vs. long-term interests. a) Examine the diagram to the right, and describe one example of why this might be good for the U.S. in the short term but bad in the long term.b) Now give an example of why this might be bad for the U.S. in the short term but good in the long term.

Name________________________ 7

7) (10 pts) Much of understanding the processes of climate change involves understanding the ways that different Earth systems interact with each other, often through “feedbacks” that can amplify or minimize a change to part of one system. This diagram shows a set of feedbacks that would result from global warming. Some amplify the warming (“positive feedback) and some diminish it (“negative feedback”). a) Explain how deforestation can have both warming and a cooling effect.b) Explain how increased humidity can have both a warming and a cooling effect.

Name________________________ 8

8) (10 pts) a) Only about half of the carbon dioxide that we have emitted through burning fossil fuels is in the atmosphere. Where has the rest gone?b) Explain why it is the case that the last time there was this much carbon dioxide in the atmosphere (400 parts per million), global sea levels were about 75-100 feet higher than they are today.

Name________________________ 9

9) (20 pts)a) What is responsible for the large-scale pattern seen in this figure?b) What has been unusual about the last ten thousand years, compared to previous interglacial periods?c) Why were sea levels 25,000 years ago about 400 ft lower than today? (i.e., where was the rest of the water?)d) How might the French Revolution have been triggered by a geologic event?

Name________________________ 10