The " I always wondered" thread

[DAVOUT]

Originally posted by Urban Ranger
Because if you don't recycle plastic, not only the landfills get clogged up, but you need digging for more oil to make plastic. Right now, plastic might not be very good to recycle, but that's because the total cost, which include everything such as manufacturing, disposal, environmental cost, and social impact, is not reflected by the price. If a person needs to pay for thousands if not millions of years of renting a spot in a landfill when he throws out a plastic bag, he probably would instantly root for recycling or even reuse.

This is where capitalism and ecology should make peace : actual costs have to be paid by the end user.

[CyberGnu]

Urban:

Well, there are lots of factors you can vary though, say, temperature, presence of catalysts, rate of flow, concentration, etc. You could even try mixtures of things, what happens if CO or water vapour is present, say?

I don't remember what the object was... Were we trying to make H2 ?

[CyberGnu]

It seems I am outgunned by the PhD student Cybergnu, and the Chemical engineer Japher.

Not student anymore, I'm Dr. Gnu since a year ago

But don't feel bad, I've learned stuff from this thread too

[Az]

[CyberGnu]

How do adhesives work? What makes stuff sticky? What determines how strong a glue is? How does stuff like blutack/rubber cerment work?

Adhesives can work chemically, physically or both. There are several different modes of adhesion: mechanical interlocking, covalent bonding, electrostatic interaction, adsorption, diffusion of polymer chains, weak boundry layers, and interphase regions. So how a particular adhesive bond is formed depends on the substrate, adhesive, surface preparation, environmental conditions and even the geometry of the bond.

But I'm guesing you are most interested in "sticky" adhesives, not glue or epoxy, right?

Sticky tape works through a combination of high viscosity and mechanical interlocking.

Mechanical interlocking is a pretty simple concept. You take two surfaces with plently of ridges and bumps, you pour some kind of liquid (the adhesive) between them, and when the liquid solidifies, all the ridges and bumps sort of anchor the surfaces to the adhesive.

The trick with sticky tape is that the liquid is very viscous, so it takes a long time for it to flow into position, unless you apply pressure to it. That's why you usually run your finger on the outside of the tape after you attached somthing, to press the liquid into place.

Does this make sense?

[CyberGnu]

Hmm, is there a bowing smiley? would be hard without a waist, I guess...

[Az]

was your PhD in Organic chemistry? I presume this since you told that your job is to find new ways to break the C-H bond.

[CyberGnu]

Organic chemistry, but concentrated on applied theoretical (quantum) organic chemistry. I did some synthesis as well, but not more than 25% of my graduate work.

Right now I'm at Caltech, in charge of the theory part of a joint effort with one experimental group and our theoretical. Good times

[Urban Ranger]

Originally posted by CyberGnu
Urban:

I don't remember what the object was... Were we trying to make H2 ?

Yup.

[Urban Ranger]

Originally posted by Lincoln
I almost started a tire recycling business once. You can burn the tires and run the smoke through some type of catalytic filter and use the heat to make electricity and heat you home.

Burning them is bad, since you lose a lot of energy and material in the process. There are a couple of local guys invented a process to recycle tyres into building materials, such as bricks for pavement.

Originally posted by Lincoln
But I am amazed at the several layers of packaging now in almost everything we use.

That is an enormous waste of resources.

Originally posted by Lincoln
It seems like the old fashioned barrells full of beans and rice etc. produced much less waste, especialy if you bring your own container to the store.

Japan is probably at the forefront of environmental conservation, since their island country has no space for landfills.

[Jaguar]

Originally posted by CyberGnu
Urban:


You mean something like
2FeO + CH4 -> 2Fe + CO2 + 2H2?

Thermodynamically unfavourable, unfortunately...

H2 is not a terribly stable molecule, so in order for the reaction to proceed you need to use the H2 in a reaction of some kind.

I think I understand this. I'm not gonna even start to look at the next post.



I've always wondered how parrots can talk when they (obviously) do not have much in common with us. Why isn't it easier to teach apes to talk?

[Urban Ranger]

Apes have smaller mouths, and their vocal cords are a lot more restricted than ours. Smaller mouths mean less room to move the tongue about.

[SpencerH]

Re: The " I always wondered" thread

Originally posted by GePap

I will start:

why are humans so physically weak when compared to other apes? A 200 lb chimp or orangutan is much stronger than a 200 lb man (a fit, healthy one, even a muscle bound one)..so, again, why is this?

I'm not sure that a 200lb chimp is stronger than a 200lb human. How would that have been tested?

I have heard many people comment on how strong monkeys are for their size. It is possible that monkeys and non-human apes have evolved with more fast-twitch muscle and with ligament/tendon attachments and flexibilities that give more strength than humans. I think, though, that the answer is mental/social rather than physical.

Factors governing the application of strength for both monkeys/apes and us will include learned reponses (ie if you grab a berry too hard you'll crush it to pulp) and fear of injury (ie nerve responses to stretched muscles and tendons). More importantly, humans also learn very early on from their parents to not apply their strength for various social/societal reasons. Thus, a monkey has less mental inhibition to exerting itself than we do, will exert a more substantial portion of its potential strength than we will (without training), and will seem very strong for its size. On the other hand, I doubt that a 200lb chimp could be trained to bench press 400lbs (as I can). Not because it isnt as physiologically strong, but because it isnt as mentally capable of pushing itself beyond its mental inhibitions against injury. In fact, overcoming the various mental inhibitions to exerting your strength is a big factor that separates experienced from inexperienced weightlifters.

[TheStinger]

A 200Ilb Chimp could rip a mans arms off. They could kill you no problem

[Urban Ranger]

Re: Re: The " I always wondered" thread

Originally posted by SpencerH
I'm not sure that a 200lb chimp is stronger than a 200lb human. How would that have been tested?

They can exert a much higher stength for their body weight.

Originally posted by SpencerH
On the other hand, I doubt that a 200lb chimp could be trained to bench press 400lbs (as I can).

Well, chimps don't weight that much. If you find a gorilla, for example, it can bench press a whole lot more than you.