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1answer
37 views

Is there a textile like material that can act as a spring? [on hold]

Imagine some sort of textile (as in very light, not metallic) that is tightly rolled up, can be easily unrolled by applying some force (i.e pulling it) but when released will eventually return to it's ...
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0answers
22 views

Fabric that allows through uva, but blocks uvb [closed]

I'm wanting to get a fabric that allows through uva, but passes through uvb. I'm not sure where to even start on this. How do I find a material with these desired properties? Allows: UVA 400 nm - ...
2
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1answer
25 views

Examples of nearly perfect fluids and gases

When learning for physics (hydrodynamics and gases) I wanted to know what would be examples of nearly perfect fluids (no surface effects and no friction) and perfect gases (only elastic collisions and ...
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1answer
47 views

Is electrons ability to produce mechanical motion considered the only reason for it to be material particle?

"Cathode rays (streams of electrons) produce mechanical motion of a small paddle wheel placed in their path indicating that they are material particles."$_1$ Isn't this statement wrong? Assuming ...
2
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2answers
57 views

Materials with directional friction property?

At the macroscopic level a simple metal file or rasp creates a large amount of friction in one direction and a much smaller amount in the opposit direction. Shark skin displays the same properties due ...
3
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4answers
512 views

What is difference between white objects and transparent objects as far as photons are concerned?

Transparent materials let photons through because the energy gap of electron is so large that the photons cannot be absorbed. If the material absorbs a photon, the photon disappears; does this mean ...
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0answers
46 views

What metals much harder than steel can be met in real life? Like pins in clothes security tags [closed]

Once I bought a piece of clothes and forgot to remove magnetic tag in the store. I found, that it consists of two disks, connected with thin pin (of some metal). I was sure it is possible to break ...
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3answers
180 views

Breaking two ropes. What can be said about the tensions?

This is a theoretical problem. Suppose we have two ropes of the same material and diameter, but differing in length. We excert force on both ropes until they break. Let rope A be the longer one. What ...
0
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1answer
70 views

What Material for reflective surface of a solar grill/barbecue? [closed]

I have been planning on building a solar grill for quite a time now, and the one problem, which is also the biggest - I need to shape a mirror into a paraboloid, so it bundles solar energy ...
0
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0answers
36 views

How do I determine $\phi$ in a hollow circular cross section using torsion equivalence?

I know that the maximum shear stress $$\tau = \frac{T}{J}\rho$$ where $\rho$ is the radial distance from the center of the cross section. I have also determined the torsional constant $J$, which is ...
1
vote
1answer
118 views

How does air escape from a pneumatic tire?

Obviously, it is caused by the difference in pressure between the inside of the tire and its surrounding environment; but how specifically is the air escaping?
0
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1answer
63 views

4 element super conductor without oxygen and iron

I am trying to find a list with super conductors. In particular I am searching for a superconductor, that consists of 4 elements none of which is Oxygen. The reason I rejected Oxygen, is because(from ...
1
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1answer
99 views

Electrons of conductors Free? [duplicate]

Are electrons of any conductor really free ? I mean are they always already moving or do they move only when electrostatic field of some sort is applied across them. I suppose if they were always ...
6
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1answer
177 views

Why can we skate on ice? [duplicate]

I have known the reason why skate can slide over ice is that water's melting curve in terms of pressure and temperature has a negative slope. If the pressure due to our mass increases sufficiently ...
0
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1answer
74 views

How long will it take to temperatures of two solids to become equal?

If I have two solids with commmon area where they are touching each other, is there any way for calculating the time it will take to them to become equal? For example, I have two blocks of different ...
3
votes
2answers
95 views

Does the material of the slits affect the pattern of the electrons in the double-slit experiment?

The question comes from thinking about the way how electrons act on the slits. Do material of the slits affect electrons motion? Assume the radius or length of the slits are set in this case.
0
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1answer
187 views

How can counting the number of cracks in glass tell you about the speed of impact? [closed]

A recent article, Counting cracks in glass gives speed of projectile (Andrew Grant, Science News, May 1 2013) indicates that the number of cracks in a broken glass can tell you information about the ...
1
vote
1answer
55 views

Glass properties

This is a question about the properties and strength of glass. I know that glass is an amorphous solid but I am not sure if that is relevant to my question. My question is that if there's no physical ...
0
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4answers
286 views

Blocking an IR camera [closed]

What kind of material would be best to block an IR camera? Would Silicon work? (e.g the Silicon typically used in iPhone cases) Rather than covering the object/subject, I'm interested in fully ...
2
votes
1answer
193 views

Abacus about the thermal expansion of copper

I am currently working on the measurement of the coefficient of thermal expansion of copper. In order to compare my experimental results with theory or experiments made by others, I am looking for ...
1
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0answers
238 views

X-Ray transparent material [duplicate]

I am looking for a material which is fully transparent to X-rays. In addition, it should be solid enough to serve as a substrate on which I will deposit some biomolecules.
0
votes
1answer
89 views

Reflectance and Absorption properties of X-rays

Are there any materials that are mostly "transparent" to x-rays? Such as glass would be to the visible spectrum? What about materials or surfaces that reflect x-rays? Does most metal reflect x-rays? ...
2
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0answers
139 views

Where can I find a complete list of metamaterials up to today?

Where might I find a list of all the metamaterials up-to-date?
2
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2answers
160 views

Is there a Transparent, Non-Magnetic Conductor?

I am looking for a transparent (visual wavelength: 390 to 750 nm), non-magnetic (not attracted by a magnet) electrical conductor that could be used for a physics demonstration. Is there such a ...