Reference: Van Heuvelan, A. (1986) Physics: A General Introduction, Harper Collins.

Sharon and Stanley are building their dreamhouse. They have already designed the layout of all the rooms, with the help of Stan's father who is an architect. You are good friends with Sharon and Stan and since you've just studied circuits in your physics class, you are interested in the wiring plans for the new home. Sharon tells you that the house will have 4 bedrooms, a family room, living room, dining room, 2 bathrooms, a utility/wash room, and a combination kitchen/breakfast area. Stan tells you that he doesn't know how many circuits his house needs in order to be safe. In fact, Stan isn't even sure he knows what a circuit is, or how a circuit breaker works. Does he need some 240 V lines as well as 120 V ? What voltage are the electrical lines coming into the house? How are the ratings on the circuit breakers determined? How are houses wired?

Using your knowledge of physics, answer Stan's questions. If you don't know the answer, where can you find the information you need? What questions should you ask Sharon and Stan in order to determine their wiring needs?

(When finished with these questions, ask your instructor for page 2.)

(page 2)

Sharon tells you that they will have many appliances in the kitchen. A microwave, refrigerator, blender, toaster oven, toaster, can opener, electric fry pan, electric wok, mixer, clock radio, clock, crock pot, and dishwasher. Stan says that his computer and printer, and Sharon's ironing and sewing "stuff" will be in the same bedroom. Stan uses an electric razor, while Sharon uses a blow dryer and curling iron in the main bath.

They also inform you that in the morning, Stan cooks breakfast while Sharon does her hair in the bathroom. And in the evening, while Sharon cooks dinner, Stan works on his computer or watches TV in the living room. Sharon likes to sew or iron while Stan does the budget on the computer.

They show you a sketch of the floor plans for the house. The dimensions of the rooms are as follows: kitchen: 12'x15', living room: 15'x25', spare bedroom: 10'x12'.

Is there a minimum number of outlets that must be wired for each room? How are overhead light switches wired into the circuit?

Sketch the wiring diagram for the kitchen. Do you need more than one circuit breaker for the kitchen? Design the wiring so that no circuit breaker opens while Sharon is using several of her appliances cooking dinner. Be sure to give several examples of multiple appliance use.

When you have answered these questions and sketched the wiring diagram, check with your instructor before doing the final activity.

Construct a wiring plan for the kitchen, main bathroom, spare bedroom, and living room in the new house with the minimum number of circuits which will still suit Stan's and Sharon's mode of living. Your design should insure that no circuit breakers will trip during the busy mornings or evenings. Be sure to include the normal items in rooms (lights, stereo, VCR, etc.) as you plan your wiring diagram.

Written by Barbara J. Duch
May, 1995; Revised January 1996

Write the summary equation for photosynthesis. Why is photosynthesis an oxidation- reduction reaction?

How were fossil fuels formed? What effect is the burning of fossil fuels and the clearing of forests having on the carbon cycle? What is the possible consequence to the earth's climate?

Reference: End of chapter "Making Connections" and study questions from McFadden and Keeton, Biology: An Exploration of Life. Norton, 1995.

Reference: End of chapter "Science, Technology, and Society" question from Campbell, Biology. Benjamin Cummings, 1993.

(page 1)

John H. Martin, the director of the Moss Landing Marine Laboratories, thinks the potential problem of global warming could be addressed by dumping iron into the ocean waters off Antarctica. He and his coworkers have demonstrated that the amount of chlorophyll found in ocean water samples collected (in 30 L botttles) from the Gulf of Alaska can be increased up to nine-fold by the addition of iron.

When they repeated this fertilization experiment with samples collected from a few hundred miles off the Antarctic coast, he and his colleagues found that for every unit of iron added to antarctic sea water, the organic carbon content increased by a factor of 10,000.

What is the basis of Martin's premise that seeding the ocean with iron would help combat potential greenhouse warming?

What organisms found in sea water account for the increase in chlorophyll content and increase in biological productivity Martin and his research group observed?

(page 2)

Martin thinks that analyses of 7,000-foot deep Antarctic ice cores provide support for his premise. He makes particular note of CO2 and iron concentrations found 18,000 and 160,000 years ago, about the time of earth's ice-ages. This information is given in the plots shown on the graph below.

(Note that scientists think that the iron found in the ice core came from dust that settled out of the atmosphere, and that the CO2 came from air trapped in bubbles in the ice. The current level of CO2 in atmospheric air is about 350 ppm.) Do you agree with Martin that the information provided by ice core analysis supports his hypothesis? Why or why not?

(page 3)

You are particularly interested in Martin's ideas, since you've just agreed to serve on a study section of a panel of the National Science Foundation (whose task is to review grant proposals and assess their funding priority). One of the proposals you must review is one by a team of scientists who'd like to test John Martin's ocean seeding hypothesis on a 60 square kilometer plot just south of the Galapagos Islands.

You're aware that the idea that biological productivity of ocean waters can be increased by seeding is not a new one. For example, other studies have shown that when nitrates or phosphates are added to the relatively iron-rich, but nutrient-poor water (by comparison with Antarctic) found in most open oceans, a phytoplankton bloom results. You are puzzled by why the grant applicant (and Martin) think that seeding the nutrient-rich Antarctic waters with iron is a better approach than seeding the relatively iron-rich Atlantic waters with nitrates or phosphates. The applicant has not adequately explained the rationale behind this approach. In addition, you're not sure if the applicant's calculation of the amount of iron that would be needed is a realistic one.

Your primary concern, however, is that the applicant hasn't adequately addressed the possible ecological impact of such a large-scale endeavor. You can't decide if this is the most lame-brained scheme of the century, or a brilliantly creative solution to a serious problem for the planet's future.

Will you recommend funding this project? Why or why not?

Reference: This problem was based on an article by Robert Kunzig in the April, 1991 issue of Discover magazine entitled, "Earth on Ice."

Written by Deborah E. Allen
August, 1993; Revised August, 1995; January, 1996

"http://www.udel.edu/pbl/cte/spr96-phys.html" Last updated Feb. 20, 1997. Copyright Barbara Duch, Univ. of Delaware, 1996.