Earth Definition and 1000 Threads

I was discussing the Fermi Paradox with a coworker at lunch and he made a very good point that I hadn’t considered and I don’t really hear mentioned on the topic: distribution. The assumption that if ET was everywhere, we should see it everywhere. The point was that that should be true for...

The History Channel has developed a series on "How the Earth was made". My wife has been listening to it in the evening and I've caught some of it. Mostly good, but the narration mentions some unnecessary commentary, and in the first program, it gets the description of carbon-14 uptake wrong...

Just something dumb but funny to think about. Redshift indicates the object is moving away. The Earth orbits the sun The sun appears to be red. So in conclusion, the sun is running away and the Earth is chasing the sun. Lol hopefully that lightens your evening.

Suppose two objects, A and B, with large lengths LA and LB, and masses MA and MB, collide at time t0. Both objects before collision are vertical and aligned concentrically, being object B positioned initially at a higher z coordinate than object A. The bottom end of object A is rigidly...

I was hoping to hear some discussion about this eventually. It is one of the biggest events in all of human history if it is true isn't it? https://www.cnn.com/2022/04/13/world/interstellar-meteor-discovery-scn/index.html

"If the Earth were not spinning, you would be heavier as you would feel the full force of gravity."so how does this apply to the moon? the moon does not rotate and therefore you would experience the full force of gravity as stated above,yes,,yet the appolo missions film footage showed...

Consider the following example: Point A has coordinates 45 lat, 0 long. Point B has coordinates 45 lat, 2 long. Both points are 5000 ft above sea level. The distance between them is X. Point C has coordinates 45 lat, 100 long. Point D has coordinates 45 lat, 102 long. Both points are at sea...

Is the Earth getting closer to the sun from gravity?

Hey guys, I have object i know its mass and velocity so i have energy. I need some king of classification of what impact it will make if it hits earth.

We know that the centripetal force and the tangential velocity is responsible for the motion of Earth around sun. Newton’s second law says F=ma. If we all get together(whole population) in one place like parallel to the tangent to orbit and jump can we displace Earth from its orbit?

I am confused how I am supposed to figure out the answer if I do not know the mass of the earth? Do I just set it to 1 and use m1 and m2 as ratios?

Hello, this is a repost from a much less-clear question I posted before (link to question: https://www.physicsforums.com/threads/triangles-inside-a-circle-to-represent-raypaths-inside-an-ideal-earth.1011998/#post-6596165). It's kind of a loaded question, however it can be expressed as triangles...

I have managed to get some of the required distances and angles. I have the distance ##a##, the velocity inside the mantle, the total radius of the Earth ##R_t## as well as mantle and core radii. I have also figured out the angle of incidence, however I cannot get the refracted angle with the...

How does the Earth's reference frame "know" to experience the gravitational pull of where the sun/Earth barycenter will be in 8 minutes, rather than orbit around the spot where the barycenter was 8 minutes ago? The latter case seems required by the finite speed of gravitation, but coplanar...

My attempt: Let ##M_e## be the mass of the Earth and ##M_m## be the mass of the person. Let ##D_{EM}## be the distance from Earth to Mars and let ##R_e## be the radius of the earth. Defining these constants (leaving off units for brevity): Masses in Kilograms (G is not a mass but I'll leave...

From the givens: Approximate Earth as a sphere: ##I_e = \frac{2}{5}MR^2 = \frac{2}{5}(5.97x10^{24})(6.371x10^6)^2 = 9.69x10^{37} kg*m^2## ##\omega_e = 7.29x10^{-5} \frac{rad}{s}## To calculate the rate of precession of the disk the Earth precesses around (1 revolution every 26,000 years)...

I am considering writing a story that features aliens indigenous to a planet orbiting a red dwarf star. Even so, because of its proximity to the red dwarf, the planet's surface receives much more radiation than Earth's surface does. What is more, the planet has no moon to stabilize its...

I know that in Earth, an astronaut feels weightless in orbit but actually is not. The astronaut would not feel his own weight until he actually stands on a floor where his feet point towards the Earth as the Normal Force is the perception of weight. So, in Jupiter, where g ~ 25, an astronaut...

Science involves not just knowing what you know, but accurately estimating how sure you are of what you know and having a decent understanding of what you don't know. There are two known true planets closer to the Sun than Earth (Mercury and Venus, neither of which has a significant moon), both...

Hey! I had a question about this problem. I did (1) Using $$R_{0}=\rho\frac{l}{A}$$ For (2) I assume the question means that the radius increases by a meter. So I used $$\bigtriangleup L = 2\pi (r_{E}+1) - l$$ and then I used that L to find the new R. Then I said $$\bigtriangleup R = R-R_{0}$$...

Mass of a satellite is 750g(##m = \rho V = 8,96 \frac{g}{cm^3}\cdot (\frac{4\pi(100cm)^3}{3} -\frac{4\pi(99,9cm)^3}{3}) = \approx 750g =0,75kg##) I am not sure what to integrate. I solved T there but it seems far stretched $$T =\sqrt[4]{\frac{dQ}{dt}\frac{1}{e\sigma A}} $$ How to get the...

Context: I'm building an off-grid, 100% solar powered home. I have a 12 kw solar array wired up to a Sol-Ark inverter and a Fortress 18.5 kwh lithium battery. Question: What is the ideal grounding/earthing scheme? Additional context: where I'm building, there is currently no requirement that...

I am just wondering if placing the Earth equidistant from 3 black holes that are spinnng would slow down time on the Earth, due to the time dilation effect. Would that give us more time to live?

He explain escape velocity in example where rocket goes straight up,isnt escacpe velocity ,velocity where centrifugal forces and gravity are equal,so refers only when rocket going in circle/orbit? Can rocket really leave Earth in straight line like he show in video once reach this velocity and...

It's a simple application of Newton's third law to show that the Earth indeed does accelerate towards an object as it falls towards earth. M_o is the mass of the object M_e is the mass of the earth From the third law (and ignoring air drag): M_e * a_e - M_o*g = 0 (with a up-positive...

A question to physicists: What sort of real world scenario / image would *best* depict the increase in gravitational potential energy in a radial field? Would a rocket traveling through the Earth's atmosphere suffice or are there better alternatives? This image would have to be relevant to the...

These folks looked to the plants growing on the driest land on Earth -- the Atacama Desert. They collected some plants, soil, and the bacteria in them; then genetically sequenced them to see what's needed; over a 10 year period...

The Burst and Transient Source Experiment Earth Occultation Technique https://www.semanticscholar.org/paper/The-Burst-and-Transient-Source-Experiment-Earth-Harmon-Fishman/b4e57f91de6fec73fa680bcd7d6efbdf0de10bee In **Appendix B**, the authors derive the equations for the occultation times...

Hello, I am attempting to correctly solve this problem, however I end up with an equation that is slightly different as the one provided in the textbook solution. For question (a) I get the same thing, just instead of cos, I have cos^2 and I can't figure out where I went wrong. My process was...

My questione are these: -If i have a voltare source (like a battery) that supplies a 5V voltage difference between its terminals, and there is a parth from positive to a resistor and then to ground, with negative terminal not connected: the current flow to the ground?( I believe because there is...

Summary:: A proposal for keeping the Earth intact during the Sun’s Red Giant phase. The following is a hypothetical method for keeping our Earth in the Goldilocks zone during the Sun’s Red Giant phase offered for analysis and critique by those amongst us who are more knowledgeable than I. Your...

There's a classic physics problem that is: If Earth is orbiting the Sun at 1 au from and is suddenly stopped. How long does it take to fall into the Sun (neglecting the size of the Sun/Earth)? I know that a clever way to solve this problem is by using degenerate ellipses and an object...

The question is simple. The molten stuff inside the Earth will get a smaller volume when it solidifies. Will the Earth increase its rotation speed in reaction to this? What about the magnetic field?

I was just looking up at the stars wondering how long they have been visible for. I started wondering if any of them might have been around this galactic neighbourhood long enough and long lived/old enough that the dinosaurs could have seen it. Do you think they’d be any? If not what might be a...

I was wondering, we constantly assume the reference of zero potential is the surface of the Earth. But if we consider the reference to be the infinity, what would be the electric potential of the Earth? As Faraday says, the Earth is charged with a -580 kC of negative charge. If we consider...

The actual problem can be found as #2 on this link: https://ocw.mit.edu/courses/mechanical-engineering/2-71-optics-spring-2009/assignments/MIT2_71S09_ups1.pdf I rewrote the problem above with the solar irradiance data that they give. My interpretation is of a square 1 m x 1 m plane sitting...

Hi Normally our electrical equipment systems neutral to Earth voltage showing 1.4 to 2 volts AC. Our requirement neutral to Earth is 0 volts. How to achieve this value ,please help me. What is the normal acceptable voltage of neutral to earth.

Would an observer many light years from Earth (and approaching say) see events leading onwards through time (to what level of detail i am not proposing but say weather and maybe Humans on the ground?) in the light received?

By "accumulation", I mean depth at the Earth's surface (i.e., whatever volume it is would be divided up the surface area). This dust would be from anything (e.g., meteors, stardust, etc.), but would only count stuff that ends up as dust (i.e., no gas or liquid). I guess a follow-on question...

I am confused. See my diagram below. With the Earth rotating, I think the scale would read the force of gravity or 448.4 N. If the Earth were not rotating, would the scale read less or more due to the effect of centripetal force? I tend to think more by an amount of 1.78 N. Is this correct? If...

The story is that I did some wiring additions ` couple of years ago. I extended a Ring Main (cover your eyes dear US readers) and bought one of those socket checkers for a few quid. I have got this far in my life without one but I though why not splash out. The connections, of course, checked...

If I assume the nebula is a circle, than the length of arc viewed from Earth is a half of the circumference. So, here $$l = \frac{1}{2} \pi D$$ From the problem, ##D = 125 000 ly##. Because the distance of nebula is much larger than the diameter; I try to approximate R with the distance of...

Good day, If I consider my system to be an object and the earth, and the object is on the surface of the earth, then the system will have gravitational potential energy. Why couldn't I say that only the object (considering it as my system) has gravitational potential energy? Thanks

Hi. can you help me to plot orbit around Earth with sphere in MATLAB? I wrote the code that plot 3D orbit but without earth. the code: clear all close all clc R=6371e+3; r0=3e+5; p0=[R+r0;0;0;0;10000;0]; [t,p]=ode45(@sattelite,[0,12000],p0); xout=p(:,1); yout=p(:,2); zout=p(:,3); vx=p(:,4)...

Mars underwent a biologically induced change (assumption -- via photosynthesis) to the atmosphere billions of years ago. Rock strata were identified that are evidence of an earlier atmosphere, that is different from what came later. The more recent atmosphere oxidized iron in most of the...

I'm taking a geophysics class and the math makes sense but the context is lost on me. My understanding is that the primary use of seismic ray-tracing is to locate disturbances that cause waves to propagate radially. I also understand that 35km is the depth at which the Earth's spherical shape...

An asteroid that will be the largest during the year 2021 is expected to pass by about two million kilometers from Earth without the risk of colliding with it, but this astronomical event will allow scientists to study this celestial body more closely. This asteroid is called “2001 FO32”, and...

Well, okay, I should say: what does Newtonian gravitation look like in a ##2+1## dimensional Newtonian universe? Consider a flat Earth, i.e. a region ##\mathcal{E} = \{ (x,y): x^2 + y^2 \leq R \}## with mass density ##\rho##, then for ##r > R## a natural guess for the gravitational field seem...

If the Earth did not rotate, would one side always face the sun and the opposite side always be in darkness? Or would a day be six months, and a night be six months? Or something else?

The Earth's circumference at the equator is 24,901 miles, or 40.075 million meters. It rotates completely once a day or in 86400 seconds. The speed of sound is 343 m/s and the Earth moves at the equator at 40.075 million m/86400 s = 463.831019 m / s which is clearly faster than the speed of...