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Re: [Phys-l] Microwave door. Was: Re: About the "why" and "how" questions.



The air rifle was a suggested Deus ex machina.

Better to check for glass by hardness; mild steel scratches all (AFAIK) P's and only hard steel (high carbon) will scratch soft glasses. I've seen shattered plastic.


I don't think your plastic will flow (be plastic), it's instead tougher and less brittle than glass -- E may be greater w/ glass, but has a lowere elastic limit. For example, PET's strain limit is 50=>150% while a Be metal glass is 2%.

Typical toughness comparison: polycarbonate 30kJ/m^2 soda glass 0.01kJ/m^2

finding the toughness (e.g. charpy impact) instead of stress cracking was difficult for glass (so very low!)

SCC of Glass Shelf

plastics (door window likely polycarbonate --lexan)

What Can Plastics Do? :: DuPont Engineering Polymers



The etymology:
Etymology
From Latin plasticus (“of molding”), from Ancient Greek πλαστικός (plastikos), from πλάσσειν (plassein)

bc

On 2010, Dec 27, , at 08:59, Moses Fayngold wrote:

When I examined the splinters, they were all sharp and crisp, which is
characteristic of broken glass. I think it is unlikely that plastic would (if at

all) produce such splinters. By all evidence, it looks like there were no
plastic layers in that window. If there were, they would probably absorb all
possible stresses due to sufficient plasticity (forgive the tautology) and
remain intact, in which case there would be no holes in the window.
Air rifle is 100% excluded.

Moses Fayngold,
NJIT

________________________________
Bernard Cleyet wrote on Sat, December 25, 2010 8:32:34 PM:

Doors curious. We have four three are double plastic no stress built up
there. The fourth and newest has a glass front and plastic rear w/ the mesh.
Any one about w/ an air rifle?


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_______________________________________________
Forum for Physics Educators
Phys-l@carnot.physics.buffalo.edu
https://carnot.physics.buffalo.edu/mailman/listinfo/phys-l