GGRA02H3 Lecture 4: GGRA02 Lecture Four.docx

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violethare736

13 Apr 2012

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Demand for food grew in europe and north america and population moved from rural to urban. Main change occurred in food consumption: stop producing it yourself, no longer able to grow on food, have to pay cash and buy food (immediately economy plays role) established a cash market . By 1930 urban population rural in canada, continue growing demand for food. Refrigeration (canning, freezing) strong food ; technological changes which made it possible to move long distances and move foods like grains and meats could be transported efficiently. Meat from south america and argentina became major supply to europe. Need to become more efficient; more products using pesticide. Substitution of natural by artificial processes and ingredients ( example- feed cattle processed food [grain] all day tied up in barn to milk them) Preservative; injecting antibiotics / growth hormones in order to reduce disease and fatten livestock.

Related Questions

It is currently popular for automobiles to use 10% ethanol / 90%gasoline mixtures (âgasoholâ) as fuel. According to popularconsensus the main benefit of gasohol use is that it âreduces ourdependence upon foreign oil.â We test this assertion by making someelementary calculations. Our analysis will unrealistically ignoreengine maintenance issues associated with older automobiles (suchas gasket and seal hardening), added fuel consumption necessary toproduce grain used as a feedstock in ethanol production,incremental food price increases associated with a reduction ingrain stocks, and many other effects. Gasohol use typically reducesaverage fuel economy by approximately 15% and effectively leavesfuel prices unchanged. This article further debates the wisdom ofethanol use and may be of interest outside the problems:
http://harvardmagazine.com/2006/11/the-ethanol-illusion.html
These concerns and problems have been strongly influenced byconversations with Dr. H.J. Harmon, of the OSU physicsdepartment.

2. Consider a 14.2 mpg 1991 Ford F150 driven 761 miles. Calculatethe pure gasoline consumption of this truck when: a) usinggasoline, and b) when using gasohol (with its attendant economyreduction). Determine the total CO2 emissions for each fuelassuming all fuels produce 20 lbs of CO2 per gallon. Comment uponthe wisdom of using gasohol versus pure gasoline in this vehicle.

Situations arise in engineering when we want to control the flow rate of a solution. This solution could be pumped into a holding tank, distillation column, heat exchanger, reactor, etc. This means that the flow rate becomes a function of time. When we turn on a pump, the flow rate is (for the most part) constant. The problem is that we may want the flow rate to be very fast at first, and then very slow towards the end of the process. This is especially true in certain chemical reactors where the concentration of reactants is always important. Control systems that could handle this type of situation are very expensive. Pumps (relatively speaking) are cheap. So, having a bank of pumps will usually solve the problem. The pumps are simply turned on or off to regulate the flow. Mathematically, this amounts to taking the volumetric flow rate function and finding a piecewise-linear approximation. Suppose that, because of the application we are running, we need a flow rate given by the function ,where t is in hours and v(t) is in 100 cubic feet per hour (e.g., v(0)=1 which means that at time t=0, we need a flow rate of 1*100=100 cubic feet per hour). Find a linear approximation and a piecewise-linear approximation using first two lines and then three lines. Think about what using more lines would do to the approximation. You will need to find suitable values of t to be able to find your approximation. As a further exercise, try to find values of t for your approximation that keeps the error (i.e., the difference between the approximation and the real function v(t) ) less than 0.1.Hint: to help with this, ask yourself this question: where would more lines be useful - where the function changes a lot or where the function changes a little?]

This geometry task may be helpful for devising amathematicalprocedure for the next lab.

A right triangle has legs ofknown lengths 2L and h. Find thelength of the line segment x whichis parallel to side h. Explainyour reasoning. Image in weblinkbelow:

http://paer.rutgers.edu/194/Downloads/194LAB07.pdfRY4bB71082bfFuqzISDrWGDOWfNgGl208qJNQTAhpzWjb_ahDlhGHPLz19S1Eq95&q=cache%3AnpyQu9LlzykJ%3Apaer.rutgers.edu%2F194%2FDownloads%2F194LAB07.pdf%20this%20geometry%20task%20may%20be%20helpful%20for%20devising%20a%20mathematical%20procedure%20for%20the%20next%20lab.%20A%20right%20triangle&docid=5c8a26db354186a31ce6383

POSTSCRIPT: EFFECTS OFASSUMPTIONS

The marbled murrelet is asmall bird that lives in the PacificNorthwest where old-growthforests are close to the sea. It nests inthe forests and feedsoffshore. It is now highly endangeredthroughout its range, whichextends from Northern California toAlaska.

These birds are extremelyvulnerable to loss of their habitat,because they nest exclusivelyin the same old-growth coniferoustrees that are prime targets forlogging. Considerable efforts havebeen made to protect the speciesby restricting timber operations inthe areas in which they areknown to nest. Scientists predicted thatthe population should growback. However until recently naturalistswere puzzledand

dismayed because thepopulation of marbled murrelets did notseem to be recovering oreven stabilizing.

A recent study suggests thereason why this testing experimentin conservation did not confirmthe prediction. The scientistsoverlooked an important assumption:murrelets can also be threatenedby man's activity at sea.Overfishing has severely reduced thepopulation of small,energy-rich fish that murrelets rely upon formost of theircalories.

Climate change of uncertainorigin may have also disrupted thefood chain, and El Nino currentsmay have changed the distributionof the phytoplankton that formsthe base of all marine life.

Further efforts to preservethe marbled murrelet must be basedon accurate assumptions aboutthe origin of their difficulties.

Could naturalists have betterconsidered their originalassumptions years ago? What would yousay?

GGRA02H3 Lecture 4: GGRA02 Lecture Four.docx

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