Earth Definition and 1000 Threads

I have learned that the gravity at the center of the Earth is zero. I guess its because it gets balanced as the force from all the sides are equal in magnitude and opp in direction. But several land forms throughout the world having different masses could cause a distortion which could make an...

Hi, I was given the following question: Show that Bose condensation does not occur in 2D. Hint: The integral you will get when you write the formula for N is doable in elementary functions. You should find that that N ∝ ln(1 − e βµ). I do indeed find that N ∝ ln(1/(1 − e βµ)) ∝ ln(1 − e βµ)...

Lets say a heavy object was resting on Earth and suddently it lost allot of mass. Will the object go up? (The loss of mass happened instantly )

Special relativity is one of the most tested theories in physics. A central postulated of SR is that the speed of light is the same for all observers in inertial reference frames, and this leads to time dilation and the other effects that have been tested with a high degree of precision. We...

Hello everyone I've a question about the cosmic microwave background which my nephew asked me a couple of days ago. How much energy hits the Earth each year from the CMB? I'm assuming here that it is measurable in this way, but apologies if not. Thanks in advance for your help. Chris

Homework Statement Okay, so the question seems really simple so I don't know what I'm missing A satellite orbits at a fixed point above the Earth's equator. Assuming the Earth has uniform density, radius R, and angular frequency of rotation, omega Find an expression for eta, such that the...

Homework Statement The Earth receives on average about 390 W m−2 of radiant thermal energy from the Sun, averaged over the whole of the Earth. It radiates an equal amount back into space, maintaining a thermal equilibrium that keeps the average temperature on Earth the same. Assuming the Earth...

why was Earth considered to revolve around the sun and nt the other way round? why is it wrong to analyze planetary motion from Earth frame?

If gravity is the warping of space, how does it work on Earth for us? Imagine a trampoline (the most common example for describing gravity) when a bowling ball is kept on a trampoline the weight of the ball forces the trampoline to stretch, but on our planet the gravity works downward on the...

Now before you excommunicate me, what I want to know is with all these sightings of galaxies 'within cooee' of the big bang, are they all in the same direction? How far can we see in the opposite direction? If we can see equidistant in both directions, would that not indicate that we are...

Homework Statement How far would be a planet from the earth, when its period would be 2 years? T = 2 years/730 days a = 150*106km Homework Equations a3/T2 = C (C is the Kepler-Constant) The Attempt at a Solution I tried inserting T in days and years, but I always get a wrong solution, since C...

Homework Statement The value of g at a point P inside the Earth and at another point Q outside the Earth is g/2. Maximum possible distance in terms of radius of Earth between P and Q is? (g being the acceleration due to gravity on the surface). Homework Equations gh = (1+h/r)-2g...

Would the gravity of Earth decrease if the Earth stop spinning? Would the gravity be affected at all? Does the gravity of other orbiting bodies cause the Earth to speed up its rotation and slow down its rotation during the year? thanks.

Homework Statement The power cable for an electric trolley (see figure) carries a horizontal current of 330 A toward the east. The Earth's magnetic field has a strength 5.0 ✕ 10-5 T and makes an angle of dip of24° at this location. Calculate the magnitude and direction of the magnetic force on...

Why Earth rotates from West to East in southern hemisphere and East to West in northern hemisphere?? Is this true,if yes then explain please.

I don't totally trust to some argument in theories about The Earth Magnetism. That's why I keep researching. I find interested with this forum, that's why I join. Although I join to offer nothing at the moment, but hope to offer something in future. Currently I enjoy with reading your...

Homework Statement Calculate the height of a geo-stationary satellite of earth. Gravitational force of earth=6.667 x 10^-11 nm^2/kgm^2 Mass of earth=6x10^24 kgm Radius of earth=6400 km V=86400 Homework Equations GM/r=v^2 r=R+h The Attempt at a Solution I plugged everything into the equation...

I want to drop a rocket-shaped object from a near-space balloon, with the aim of maintaining a downward acceleration that leaves it's contents in microgravity. I think that this means: The (unpowered) rocket needs to maintain as close to 9.8m/s2 acceleration in order to balance out the...

AS: If this is not the right place to ask this question, please let me know where I could try. Thanks. AS: I had to validate the fact I used the template to post my assignment, however I didn't (but it wouldn't post otherwise - btw it's not an "assignment"). Hello everyone. I need help with a...

a related thought experiment to a tunnel through Earth through which a person falls to the other side, is what if it was a pendulum falling through the planet? first, a pendulum is at 90 degs to the G field; 2nd, as soon as the pendulum BEGINS to fall through, it is in free fall, and it will...

Hello to everybody, i have been programming an n-bodies integrator in MATLAB, in an earth-centric ECI perturbations framework. The main objective is to 'write down' in a procedure an interesting part of phisics, and secondly (at the very end of it) to get a complete integrator for meteor orbits...

From http://www.scientificamerican.com/article/moon-life-tides/ It all started some 4.5 billion years ago when, as theory has it, our nascent Earth was blindsided by a Mars-size planetary embryo, believed to have spun Earth into its initial fast rotation of roughly 12 hours per day. Can...

If the Earth was really massive, then is it possible that no sunlight will reach Earth due to gravitational lensing?

Homework Statement A rocket ship leaves Earth at 0.6c. The clock of the rocket says 1hr has elapsed. (a.) According to the earth clock, when was the signal SENT? (b.) According to the earth clock, how long after the rocket left did the signal arrive BACK on earth? (c.) According to the rocket...

I was doing some calculations using the escape velocities from Earth, Moon and Mars. Then by chance I calculated the velocities attained when an object was "dropped" from a height of the radius on each of these bodies, assuming the acceleration due to gravity remained constant during the fall...

My first question on your forum. I just found you last week and have spent a whole lot of time reading. My question: Not actually a question, but a supposition seeking confirmation. Were it possible to travel faster than light, could we "catch" the light from prehistoric Earth and see...

I'm in search for a career that is 'earth' related. I also have interests in the ocean. So, my choices come down to; Earth Sciences & Marine Biology / Oceanography. Was looking for a career in the space industry, or renewable energy, but found most of it to be engineering based. And I don't...

I have been looking for an answer for so long. Everywhere I look I find answers to the question how two lunar sized moons would affect the Earth's tides and so on. But I want to know, if we had our own moon, with its normal orbit, and an additional smaller moon, (or just further away from...

So, I have really no background in astrophysics (other than touching on some areas in general physics and calculus). I understand that asking questions such as the one in my title, that I would need to be more specific, and I will attempt to be as specific as I can. I understand that most...

Not a joke successful rapper refutes ball earth; https://m.soundcloud.com/bobatl/bob-flatline-feat-neil-tysonThe push back from Neil DT nephew;

Dear PF Forum, Lunar Satelite orbits the moon, The moon orbits the earth, The Earth orbits the sun, I know that some of you know about this picture You might want to tell me. "No Steven, the Sun also orbits the earth" But for all practical purpose, we'd say that the earth orbits the sun. So...

Rapper B.o.B. says the Earth is flat; NdGT responds by dropping a diss track*. Flat To Fact (feat. Neil deGrasse Tyson) (B.o.B Diss Track) *well, his nephew anyway.

Im picturing a stationary object at the equator of the earth, going around in uniform circular motion due to the Earth's rotation. The centripetal acceleration would point directly inwards into the Earth at all points in the circular rotation, and gravity would also point in the same direction...

Okay so to start, this is just about the most random inapplicable proposal ever, so bear with me. Its just a cool question to consider. So, here goes: What would happen, (again, this is highly theoretical) in the instance that an enormous screen - much like the ones that rests behind most...

Hi is my assumption correct ? precision gyroscope,sitting on the table during 24 hours, perfectly balanced, with free motion in all 3 axis, while still spinning using electric drive or compressed air to maintain motion... there should be relative motion between gyro and its stationary holder...

The Earth is a geodynamo. It is an electromagnet because a net current flows in the molten iron in the mantle. My question is, which way does the current flow? The northern magnetic pole is a South pole, so the magnetic field points north at the equator.

Here is an interesting phenomenon: If one were to drill a hole that went all the way to the center of the Earth and drop an object through the hole, according to a model called PREM (Preliminary Reference Earth Model), the acceleration of the object would initially increase as it approached the...

What would have happened to to the evolutionary process had the Earth's axis of rotation had no tilt? What comes to me first would be a total lack of anything based on the year calendar. There would be no deciduous trees or dormant grasses, certain animal species would have no particular mating...

Actually I would like to start with the big bang theory which tells us the age of our universe and cosmos. Literally cosmos doesn't mean only the space around us but also the life present around us. So what big bang tells us is that the universe was a small atom which exploded and started to...

Homework Statement An object possesses 61.14 kg mass. 1. How much energy in kilojoules would be necessary so as to project the object from the surface of the moon to the Earth's atmosphere at the Karman Line of 100km Earthly elevation, at such a speed that the total travel time between lunar...

From Space The first difference between our Earth and Great Lakes Earth can be seen from space. Great Lakes Earth is still the third planet of the solar system, 93 million miles from the sun, 8,000 miles wide and weighing in at six sextillion tons. But that’s that. Back home, the moon has a...

While wondering whether a hardworking crackpot can do actual irreversible damage and obliterate the earth, I did get an idea from an old book, that says that something thrown at the escape velocity never returns. Hence it may be perfectly possible to use the available energy to throw the Earth...

So I've gone through the process of deriving the geodesic equation, I thought I understood it. I hoped that once the equation was obtained I'd be able to do simple replacements and find the shortest path between two locations on earth. I'm really stuck right now though so does anyone know how...

Hello, I had a bit of trouble figuring out this problem: 1. Homework Statement Given the following, determine the distance in miles above the Earth's surface of a geosynchronous satellite. MEarth=5.98E24 kg REarth=4,000 miles 1 mile=1604 m Homework Equations Fg=(Gm1m2)/r2 FC=(mv2)/r The...

Greetings, Hi, I am new member of Physics Forums. Here is my question: How many stars can we see from Earth? and also If you know, How far can we see? Thanks!

Homework Statement So I am trying to model the motion of the Earth around the Sun using ode45. I modeled this using an euler-cromer scheme, but I would like to get familiar with using a solver. I wrote the code for an Euler-cromer and it worked just fine. However, when I try to use the same...

Homework Statement The half life of U-238 is approximately 4.4 billion years, while U-235 is approximately 700,000,000. A Uranium ore has 0.75% U-235. Assuming there was an even amount of both types of Uranium when the Earth was formed, estimate the age of the Earth. Homework Equations N =...

Suppose I am on ISS and Earth is exactly below (at the right angle to the ISS's line of path). Now if I throw one ball below towards Earth from window at exactly 90 degrees to the line of path of ISS and one ball upwards at right angle to the line of path of ISS. **Assume normal human strength...

Two satellites A and B move around Earth in a circular orbit. The mass of B is twice the mass of A then I agree that kinetic energy of B is greater than that of A. But what I couldn't understand was that why are speeds of A and B equal as given in the book. Shouldn't they differ according to the...

It is a thought I just thought of with all the wonderful attention that climate change has been getting recently. The thought goes as follows: The world has ever increasing entropy as the whole universe has so. With humans adding to this effect even if green house gases curbed due to this...