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1

We would have to know more about the ice we want to build the wall with. For example, for ice in icesheets, you have an ice which effectively reaches a plastic region of the stress strain curve at around $0,5 MPa$. I am not a geologist, but I believe that the glaciers can be only thicker than $\sim 50 m$ thanks to it's specific shape and the fact that the ...


1

If space-time of a black hole is infinitely curved, how can new volume be created for these particles to occupy? The spacetime of a black hole isn't infinitely curved. Only at the spacetime singularity within a black hole is the curvature infinite. The spacetime near, at, and within the horizon is highly curved but not infinitely so. I recommend ...


2

On paper, a black hole already has infinite density. Two coalescing holes would combine to another object of infinite density. Realistically, we would need quantum gravity to prevent a true singularity from forming,a nd there, we could address, more concretely, what happens when the "masses" in the center of the black holes merge. But until we ...


1

I've been having a play with some granulated and some icing suger (I think "icing sugar" is the same as "powdered sugar") and the thing that strikes me is that icing sugar is less free flowing than granulated sugar. I would guess this is the reason for the density difference. You mention in a comment that the packing fraction for spheres does not depend on ...


0

You measure the volume, and hence the density, using a pycnometer bottle. You weigh the bottle, then fill it with the fluid of your choice (choose one that wets your powder easily) and weight it again. The different in weight divided by the density of the fluid gives you the bottle volume. Now clean, dry and reweigh your bottle. Add your powder and ...


1

You need the crystal structure and unit cell dimensions to obtain the molar volume. Being polycrystalline rather than single crystal means your actual sample is probably slightly less dense than you will calculate. A quick Google search on 'unit cell LaCuO2' brought up a paper by Bob Cava in J. Mater. Res. 9(2) 314-317 (1993) with a table of the structure ...


0

A mole is a specific number of objects (in this case, molecules) and therefore tells you exactly nothing about density. It does allow you to calculate the mass of a single molecule. You cannot figure out the density unless you know the crystalline structure that your molecule takes on -- if in fact it does so -- as well as the lattice spacings between ...


2

The notion of buoyancy really only applies to fluids or very plastic/glassy solids, so might not be something to look at with the polystyrene beads. However, if we want to model it like a liquid, there are also the factors of "surface tension" and "viscosity" to consider: polystyrene beads are often electrostatically bound to each other, creating an ...


4

You can rearrange the terms to have any constant as the base of the exponent: $D = 1.25 e^{(-0.0001h)}$ $= 1.25 (e^{0.0001})^{-h}$ $= 1.25 (2^{\frac{0.0001}{ln 2}})^{-h}$ $\approx 1.25 (2^{0.00014})^{-h}$ $= 1.25 \times 2^{(-0.00014h)}$


10

It's actually a surprisingly straightforward differential equation. If you assume that the acceleration due to gravity $g$ doesn't change with altitude (a good approximation if the atmosphere is thin compared to the radius of the earth), Bernoulli's relation tells you the change in the pressure $P$ with height $h$: $$ \frac{dP}{dh} = -\rho g$$ Meanwhile the ...


3

Euler's constant appears naturally in phenomena where the spatial gradient of a quantity (or rate of change with time) is proportional to the quantity itself: $$\frac{\mathrm{d}X}{\mathrm{d}x} = X/x_0$$ ($x_0$ determines the strength of the proportionality, and keeps units straight.) The solution of this differential equation is $$X=X_o e^{x/x_0}$$ $X_0$ ...



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