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7
votes
3answers
124 views

How much additional light does Earth receive from the Sun due to Earth's gravitational field?

I was reading about how gravity affects light, and that got me wondering how much additional light is collected by the Sun due to the Earth's gravitational field. Is it a significant amount of light (...
0
votes
3answers
98 views

Is it possible to build planet-sized non-spherical structures?

Beyond certain size and density the celestial objects tend to admit a spherical size. I wonder if is there a fundamental mass, density or specific strength related number which when surpassed a non-...
12
votes
2answers
1k views

Energy needed for Superman to take off and fly at the speed of sound

I just watched "Man of Steel", and I'm wondering if my logic is correct. Let's assume Superman is 80 kg. The energy required to take off from the rest to reach the speed of sound in air (if I neglect ...
2
votes
1answer
47 views

How can you find the impact necessary to change the direction of Earth's spin?

If an object the mass of the moon was to hit earth's surface at an angle that would be in the opposite direction of earth's spin, how can you find how much momentum the object needs to cause earth to ...
1
vote
1answer
72 views

Cesium-137 From Fukushima Meltdown

I've been reading up on the Fukushima nuclear meltdown and its effects it had on the environment. The iodine-131 initially released from the incident decayed after 8 days, but other isotopes such as ...
1
vote
1answer
42 views

Tangent and Normal accelerations position estimation

How can I derive a particle position given it's last known positions (x,y), velocities in it's components (vx, vy), tangential and centripetal (normal) accelerations? (this is the only available data) ...
1
vote
1answer
48 views

liquid trapped in wet sponge

If you soak a sponge in water, or some other liquid, and then let it hang then some liquid will flow down due to gravity but not all, some amount will remain trapped in the sponge by the capillary ...
0
votes
1answer
87 views

What is the best way to calculate impact time with collisions?

I've been teaching myself physics and I've been wondering about the impact time in collision calculations. The scenario I've been using to learn is an object with a mass of 4000 kilograms colliding ...
3
votes
0answers
148 views

Nine Planets in the Solar System?

I just discovered that there is a Caltech team1 that suggests that there is "Evidence of a Ninth Planet": The object, which the researchers have nicknamed Planet Nine, has a mass about $10$ times ...
3
votes
0answers
64 views

Are there any connections between James–Stein estimator and quantum mechanics?

Very nice statement from wiki: When three or more unrelated parameters are measured, their total MSE can be reduced by using a combined estimator such as the James–Stein estimator; whereas when ...
2
votes
0answers
44 views

SOHO solar observatory, comet numbers and composition

SOHO discovered its 3,000th comet, cementing its standing as the greatest comet finder of all time. Prior to the 1995 launch of the observatory, commonly known as SOHO, only a dozen or so comets ...
2
votes
0answers
35 views

Quantum Efficiency Estimation

Might there be a way to do a rough estimate of the quantum efficiency of a photo-detector like a CCD or CMOS sensor based only on a picture taken with it? I've read papers and guides (like this one: ...
1
vote
0answers
24 views

Electro magnet strength to weight ratio

I was wondering. How would I work out how strong a magnet would have to be to support my weight.
1
vote
0answers
13 views

Fermi estimate for ice nucleation timescale

My friends in a Cryo-EM lab freeze their very samples quickly, a process they call vitrification. The timescale for this process is milliseconds (from wikipedia): The production of amorphous ice ...
1
vote
0answers
132 views

Orbital elevators and the Coriolis effect

Consider an orbital elevator simply modelled as a large mass in geostationary orbit (altitude approx 36,000km) around the Earth, connected to a point on the equator via a strong, light, likely ...
1
vote
0answers
1k views

What is the maximum non-fatal force withstandable by a human being for a short period?

Assuming any (optimal) body orientation/position relative to the direction of force and mechanism of death. I'd be interested in a rough estimate of threshold force and a suggested mechanism of death....
0
votes
0answers
63 views

Calculating the theoretical velocity of a projectile

Recently, I made a homemade air powered airsoft gun. I wanted to know how fast it would accelerate out of the barrel, so I tried do do some calculations, but to no avail (keep in mind, I haven't taken ...
0
votes
0answers
33 views

Is it possible that my 750ml water bottle contains spent fuel from a space shuttle launch

Firstly I live in New Zealand which is very distant from USA which is where the space shuttle was originally launched from. So what is the possibility of molecules from the rocket engines spent ...
0
votes
0answers
83 views

Can the curvature of space be measured using a swimming pool?

I read somewhere that if the center of mass of two twelve ton elephants was one meter apart then the space they curve would be one nanometer longer. (Though I doubt elephants come that dense) This ...
0
votes
0answers
157 views

Determine the amount of energy used for baking a cake

Let's suppose we have a room of temperature $T_0$ with an oven of volume $V$, both filled with air of density $\rho$ and specific heat $c$. We need to bake a cake in the temperature $T_1$. Thus we ...
0
votes
0answers
46 views

Can the half-life of rubidium 87 be theoretically estimated?

Can the Fermi golden rule be applied to give an approximation of this half-life?
-1
votes
0answers
21 views

Is there anyway formula to calculate the heat produced by the burning glass and lenses?

Am just doing a simple project with burning glass. Is there any formula to find heat produced by it relating with the focal length or magnification of lens as well as mirror too?