Is My Physics Teacher Being Inconsistent with Significant Figures?

[ShawnD]

Yes, Shawn D is correct. If you need more paper, you just use more land, more equipment, more bleach for processing the paper, dump more toxic byproducts in the water, creating higher banks of foam (ever been within ten miles of a paper mill?) and create more waste heat and toxic gasses.

Break it down this way

Recycling
-Transport paper to some recycling place
-Grind the paper
-Bleach the paper
-Remake the paper
-Transport to stores

Environmental Impact:
-Roughly the same amount of bleeching as new paper


Landfill old stuff, make new stuff
-Transport trees to some place
-Grind the trees
-Bleach the pulp
-Make the paper
-Transport to stores

Environmental Impact:
-Landfilled paper is eaten by bacteria to create methane gas which heats peoples' homes


The only common recycling process that actually saves energy is recycling aluminum cans. Aluminum from bauxite takes much more energy than recycled aluminum.
Paper, however, is the exact opposite. Recycling paper requires energy every step of the way. Landfilling paper actually has a net gain in energy since you get a similar amount of energy from the collected methane as you would if you just burned the trees in the first place; being able to use the trees as paper before collecting the energy is just an added bonus.
Plastic is another thing that requires more energy to recycle than to make new, but plastic doesn't naturally break down so I would say that's totally worth recycling.

 

[motai]

The only time we use paper in his class is for notes (in which case we must use both sides of paper) which are two or 3 pages long and quizes and tests.

Hahaha! I would do so well in that class! All my notes are highly compressed due to my extremely small handwriting. https://www.physicsforums.com/archive/t-15640_Tiny_Notetaking.html

I even have a more recent example with my AP Government notes, but id rather not get into that.

So far my personal record is 9 of my lines per 1 college ruled line, according to your teacher then id definitely be saving paper and the environment.

 

[Imparcticle]

Motai: My teacher'd love you! You know, our quizes are really short, usually 5 questions (and 7 points each...) long. My teacher gives it to us in slips of paper, so that paper can be saved. But we end up having to use our own paper to do the problems on, so this could be his way of saving money.

Your environmentalist teacher is insane. Trees, like corn, are grown on farms. If you need more trees, you simply grow more. Wasting lots of paper is like throwing out a whole ear of corn, of course it's bad, but forcing students to always use both sides is as crazy as eating the corn cob.
Sorry but I had corn on the cob for supper

lol. Very true. I think I'll tell him that. I'll come back and tell you his reply.

I have to e-mail my hmwk now...

 

[Chi Meson]

ShawnD,
What's your take on "resource recovery" , that is, places that burn trash for electricity? I have a similar attitude as yours when it comes to recycling, and I've thought that burning the plastic bags to get electricity is probably the best use of the resource if the gaseous output is "not too toxic."

That last point, depending on who you talk to, varies greatly. Our own "RR" plant in Connecticut is much cleaner than our coal-fired plants (but our "sooty six" are particularly bad).

 

[ShawnD]

ShawnD,
What's your take on "resource recovery" , that is, places that burn trash for electricity?

I support them all the way. Most hydrocarbons burn fairly clean when given enough oxygen.

 

[Chi Meson]

Yeah, I've seen the smokestack at our local RR plant. It has got to be the least opaque smoke I have ever seen coming out of any stack anywhere. I'd call myself a "wary supporter" of resource recovery; I understand Singapore burns all its trash for electricity and it's considered the cleanest city in the world. (there's never any mention of the air quality down wind, though).

 

[leright]

20 m/s^2 is definitely one sig fig...