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ANY HELP! 2!

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mousa:

--- Quote from: slvri on November 24, 2009, 01:20:08 pm ---when the flasks are connected the total volume of them both is 1+2=3dm3
now using boyle's law
for flask X:p1v1=p2v2
1(2)=p2(3)
p2=0.67kPa
for flask Y:p1v1=p2v2
2(1)=p2(3)
p2=0.67kPa
total pressure=0.67+0.67=1.34kPa

--- End quote ---

Thanks a lot slvri :D

Saladin:
Please post any problems that you may have with any of the subjects mentioned above. ;D

Saladin:
Here u go new member k..something

vanibharutham:
Hi,

There is something that i can never seem to understand in a stress strain graph....
 the difference between the yield point and elastic limit

according to my teacher they are the same thing,

according to the edexcel book:

Yield Point = the point where a small change in stress causes a large change in strain
Elastic Limit = the point up to which a material is elastically deformed


along with that doubt, there seems to be a misconception with the definitions of the words STRENGTH and TOUGHNESS...

i did some reading, and found that toughness is the energy absorbed per unit volume, and stronger materials have a high ultimate tensile stress..

Now, once again resorting to edexcel definitions:

TOUGHNESS = the property of materials to resist plastic deformation. A large amount of force is needed to cause plastic deformation.
STRENGTH = property of materials to absorb large amounts of stress without failure...

those are a bit vague... any clarification would be great

Saladin:
Yes, this is often something that we all get confused about:

At the elastic limit, the material does not move back to its original limit, but it still moves back a little. Like it gets deformed yes, but it still springs back, and becomes less than the extended length.

But the yield point is the point at which there is no going back. At this point the material shows plastic behavior, as the length to which u extend it remains like that, at this point slide between the molecules occur, as in the cations in the metal slide over each other and cannot go back to its original length, as the metal loses this energy as heat.

Now toughness and strength

toughness is basically the ability how much stress is required to get the material to its elastic limit, thus talking about tensile stress.
strength of a material is its ability to resist being necked, thus it is talking about compressive stress.

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