# Tag Info

1

No. As @Jim said, the heat would weaken the rock, which would cause a tunnel collapse before any sublimation could occur. Also, remember that the air in the tunnel would generally be at the same temperature as the rock (unless a large cooling system was put in), so thermal equilibrium would be maintained without any sublimation.

3

Correct. For a sphere of uniform density, the acceleration drops off linearly. $$g = g_{surface} \frac{r}{R}$$ where $r$ is the location under consideration, $R$ is the radius of the sphere and $r < R$. Under such a scheme, gravity would be one half that at the surface. The earth is not a uniform sphere though. The outer crust is much less dense than ...

0

In this, I have taken the assumption that the singularity is created within the atmosphere, perhaps by an experiment or some such, rather than a wandering black hole, and therefore starts life with much less mass than the earth. A naturally created black hole travelling in space would generally be far more massive, having been created from a collapsing star. ...

0

Reformulating your question: do metals feel a force of attraction to the earth due to the earth's magnetic field - and does that force depend on the position on earth? It is not the magnetic field itself that causes the attraction, it is the gradient of the magnetic field. In a uniform magnetic field you will get some magnetization (more so in ferromagnetic ...

2

Some key reading if you want to understand this stuff is chapters two to five of the IERS Technical Note 36, the IERS Conventions (2010). It's not just the J2000/FK5 frame (aka the EME2000 frame) that is associated with some epoch date. Every Earth-centered inertial frame has some epoch date. There are two fundamental reasons why this must be the case: ...

4

As a visual demonstration of Luboš Motl's answer, this: Image obtained using Climate Reanalyzer (http://cci-reanalyzer.org), Climate Change Institute, University of Maine, USA. is the average surface temperature on earth for 2013. This: is the solar flux by Luboš' formula. And here: I've tried to replicate their crazy color scheme. The point is, ...

1

The University of Arizona had a neat website that addressed precisely such questions. It's moved here now. You can choose all kinds of parameters - kind of projectile (ice / rock), impact angle, velocity, landing site and get a prognostication, expected damage etc. Really cool stuff.

8

First of all, there are no Moon-sized asteroids in the (sufficiently inner) Solar System. The largest asteroid has radius 450 km which is about 4 times smaller (64 times smaller volume) than the Moon. Moons of planets are not counted as asteroids. A collision with a Moon-sized object would of course be a terminating catastrophe for the Earth. If you look at ...

0

It actually would be possible to achieve an almost stable orbit IF you could make a trebuchet powerful enough to fire a projectile to the moon. You could get the projectiles to orbit several times at least. And as people pointed out, just making one to fire into space is practically impossible, but assuming you got past that step, you have another problem. ...

2

You can use this website to calculate the effects of impacts. If you take the distance to be 20,000 km, projectile diameter to be 10 km, the density to be 3000 kg/m^3, impact velocity 30 km/s, impact angle 45 degrees and target type sedimenatary rock, then you get this result, the only big effect is the airblast: The air blast will arrive approximately ...

1

Consider the initial pulse - it is of finite and short duration. It contains a number of frequency components, with higher and higher frequencies required for shorter and shorter initial pulses. This can be seen by taking the Fourier transform of your initial pulse. As the pulse propagates and the higher frequencies are preferentially absorbed, you can no ...

9

Earth can lose heat to space through radiation. The earth behaves roughly as a blackbody and so radiates electromagnetic radiation into space at a rate of roughly 120 PW.

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