Earth Definition and 1000 Threads

How much energy needs to be be expended to throw a non operating satellite (or other space trash) out of orbit (L4 or L5) or L2 into deeper space... thus minimizing space debris in Earth orbit. I could only find formulas for getting an object INTO orbit... Background of question: we were...

Hi All, An observer, F, stands on Earth. A spaceship, F', is also on Earth. Their clocks are set at 0. The spaceship then leaves Earth at .5c. After 10 seconds, F sends a light signal to F'. As soon as F' receives the signal, F' sends a light signal back. When does F receive this signal from...

Homework Statement Homework EquationsThe Attempt at a Solution [/B] The thing to remember is that inside the Earth surface, the gravitational field does not remain inversely proportional to ##r^2##. The equation of motion is ## \ddot r = \frac { -gr} R## ....(1) This means that the...

Hi, I'm actually a teacher presently undergoing gravitation and circular motion with my students, and ran into a problem I forgot how to think through. I'm trying to explain Newton's cannonball thought process (shoot a cannonball fast enough off a mountain and it will circle the earth), and...

we know that the moon is far away the distance between us and the moon can fit all the other 7 planets and some small dwarf planets but how ? it would take us 3 days to reach the moon and the spacecraft were traveling in at least 240,000 miles it should take us more than a year to reach the...

... where was our current place in spacetime, call it A, when that photon started its journey 12 by ago? Did A even exist 12 by ago?

Homework Statement (a) What is the escape speed from the sun for an object in the Earth's orbit (of orbital radius R) but far from the Earth? (b) If an object already has a speed equal to the Earth's orbital speed, what additional speed must it be given to escape as in (a)? (c) Suppose an...

Hey, this is going to be my first post here so I'm not sure how it all works, so just tell me if I do something out of order please. Anyway I have been given this homework assignment and part of it was the question stated below...

So I was on my way to school this morning and looking at the beach made me think of something. Why doesn’t the water on Earth fall out and into space? Like, if you really didn’t think too hard, you’d be like, yeah, the Earth is tilted, so why, doesn’t the water fall out like a glass of water? If...

Imagine we are all cavemen without satellite technology and just discovered the Foucault pendulum! As we know the angle of presession depends on the latitude. This can be used to prove that the Earth is rotating, right? Now by putting several Foucault pendula around the Earth, at equidistant...

I mean it would be impossible for Earth to be fully spherical as it would be too bumpy to be a sphere shape. If this is the case, why is Earth considered round?

Do you think AI will lead to the end of humanity, Earth, or help us colonise the Universe and prosper? Will technology and robots kill us all? I found the interest in posting this poll after reading some quotes from Stephen Hawking on the topic. Poll. Thank you.

Data for the mean Earth temperatur: - For example, the average annual temperature for the globe between 1951 and 1980 was around 57.2 degrees Fahrenheit (14 degrees Celsius). (UCAR). - The global mean surface temperature is 14.46 °C computed from MODIS data (2001-2012). - Estimated Jan 1951-Dec...

The Theia hypothesis is the current leading hypothesis to explain how our moon was created. Both Earth's mantle and the moon's surface have indistinguishable oxygen isotope ratios, which leaves the earth–moon system as more similar in O isotopes than any other two bodies in the solar system...

Homework Statement A particle of mass m is dropped from a height h, which is not necessarily small compared with the radius of the earth. Show that if air resistance is neglected, the speed of the particle when it reaches the surface of the Earth is given by ##\sqrt {2gh}## ##\sqrt {\frac {R_E}...

The suggestion is a fifth force to counter these anomalies is this generally excepted? arXiv:1711.02875 [pdf, ps, other] Anomalous accelerations in spacecraft flybys of the Earth L. Acedo Comments: 41 pages, 11 figures (Accepted for publication in Astrophysics and Space Science) Subjects...

I have entered this section of the forum and found references to Star Trek. This series once left me wondering. It was a chapter from the first era. Spok travels to the 1930s on Earth and his communicator breaks down. Asking, he manages to reach the laboratory of a scientist of 1930, who...

So I am doing the charge to mass experiment and determining the relationship between: 1. accelerating voltage and radius formed by the electron beam 2. magnetic field strength and radius formed by electron beam Theoretically I should obtain an equation of the form: r = (1/B) *sqrt(2mV/e) where...

If you had two masses, m_{1} and m_{2}, and you released them in space infinitely far apart, their kinetic energies would satisfy \frac{1}{2}m_{1}v_{1}^2+\frac{1}{2}m_{2}v_{2}^2=\frac{Gm_{1}m_{2}}{r} if they met with a distance r between their centres of mass. This equation therefore tells you...

Homework Statement The distance between the Sun and the Earth varies during the year: it is a minimum in January, and about 3.3% larger at its maximum in July. What is the corresponding change in the Earth's effective temperature? Homework Equations Energy absorbed: $$ E_{abs} = \pi R^2 (1-...

Why is the potential of the Earth taken as zero ? Putting the question in other words:: All earthing is done to the ground. Over the years every singe charge in excess is grounded to the earth. Even then why is it so that the potential of the Earth is considered to be zero ??

Mass of the Earth is 5.9 x 10^24 kg . How long has it been at this value and why does it not change even when the population of the word has gone up by many folds , there have been new flora and fauna . when was this last measurement taken?

I want to make a interactive simulation that shows whether or not an asteroid will hit the surface of the Earth. It would have 2 sliders for you to control the speed and mass of the asteroid. The simulation will output "yes" or "no" if the asteroid hits the surface. Is there a mathematical...

Please critique this logic. It's well known from chemistry that cooler water can hold more gasses in solution than warmer water. As ocean temperatures rise (slowly, for any reason, over centuries) dissolved greenhouse gasses will come out of solution and into the atmosphere. Conversely, as...

What amount of Air and sound pollution would this cause, i mean if every single person on Earth starts bursting crackers for 5-6 hours only for one day, I just need the approximate idea of dammage this would cause to environment, u could assume average values for these data, please help me, i am...

I thought about the geometry of Earth by definition and thought of the implications of 'curved space-time'. I understand a trajectory of a satellite and other objects to be straight geodesics through warped space-time. Would the Earth then therefore be able to described as a straight surface in...

Hello all, I was going through study of gravitation of earth. The book teachs that gravity of Earth is more near poles than at equator as Earth is not perfect sphere rather radius of Earth is lesser near poles larger at equator. A thought came in my mind that if the water at level goes also...

So, I was thinking today about Newton's Law Of Universal Gravitation. Well, when I was thinking, I remembered that if you were to drop a rock, the Earth would be pulled the slightest bit. Right? Anyways, if that’s the case, then if there are enough birds and planes flying around in the sky, then...

Homework Statement The International Space Station, launched in 1998, makes 15.65 revolutions around the Earth each day in a circular orbit. Find the height of the space station (in kilometers) above the earth’s surface. Homework Equations T = (2*pi*r) / v r - radius, distance between center...

I have met several people online who believe that the Earth is flat, my craziest experience is this one guy believed that "There's no universe, the sun and moon are only 30 miles away from us." I can't debate him cause I don't know a lot in those fields. Can I get some help to debate him.?

In reading Jules Verne's book A Journey to the Center of the Earth I came to a section where one of the characters questions if the massive weight of the air would be fatal at the center of the Earth. I lack the mathematical skills to derive an equation to graphically represent the results. My...

Spaceship moves away from the Earth at a constant speed of 300 m/s. How long would it take for a clock on the Earth to differ from a clock in the spaceship by 1 second.

Homework Statement 1. Homework Statement The Earth turns once around its axis in 24.0 hours. We will assume that it is perfectly spherical, with radius 6400 km. The mass of the Earth is taken to be 6.00 × 1024 kg. The gravitational acceleration on the surface is taken to be g = 9.80 m/s2 . a)...

Saving Earth - for a while: Could we shade the Earth from the Sun at a rate that keeps up with the Sun’s increase in Luminosity? There is a theoretical Dyson’s Ring that could be built around the Sun that would be used to tap the energy of the Sun. Could we construct something like that to...

What do you think?

Florence is a miles-wide asteroid that will come within 4.4 million miles of Earth on September 1. That's very close for an asteroid this size. On my twitter is an animation and a link to a simulation of Florence as viewed from Earth. It comes from the southern sky and disappears to the north...

"Today's astronomers detect objects so far away that their light has taken perhaps 10 billion years to reach us." -NatGeo May 1974 page 595 If there was a planet and the light that has been reflected from Earth was reaching there 4.5 billion year later (that means it would be 42.75 trilliard...

Are there variations of dark matter concentration on Earth based on months or seasons of the year?

I was just wondering. According to Lorentz transformations, if two events are simultaneous in one reference frame, they will generally not be simultaneous in another. The time difference that I get between the two events in the other reference frame is \Delta t^{`} = \gamma\beta\Delta x...

Dear community, I am very ashamed to have not noticed this result but well into my physics major, and I would like to share it with you. I am not sure it is right, which is my reason for posting it. The normal force is classically referred as...

Potential of a body is defined as the amount of work done in bringing that body from infinity up to some point divided by its charge. The Earth has zero net charge, so the work done in bringing any charge from infinity till the Earth is zero. So what do statements like, "The potential of this...

In this forum I read a thread about centrifuge and learned that, ''There is no difference between centrifuges on Earth and centrifuges in space because gravity is in no way related to how a centrifuge works'' Reference https://www.physicsforums.com/threads/how-do-centrifuges-work.148518/ But...

Can anyone tell me accurately. accuracy of moon orbiting Earth in how many days and hours and seconds and if it is multiplied by 14 how much it will be in days. i need accurate answer. Thanks, Ahmed.

Story in brief: An unknown agent blows up the moon, initially into 7 major pieces and a bunch of little ones. The pieces are gravitational bound, but collisions between the pieces continues the break up process. Stephanson postulates that the number of pieces reaching the Earth's atmosphere...

Pardon me if this seems like an incredibly naive question. Perhaps the question could also be rephrased as such: "Why do the laws of classical mechanics hold true with Earth as a frame of reference?" A quick google search turned up the usual answer: the Earth rotates at a constant speed...

Homework Statement The problem is stated in the picture. Homework Equations Fg=Gm.1m.2/r^2 The Attempt at a Solution I found a similar question where someone wanted to find how high will the weight be half the weight on the surface. Here is one of the answers: F =G.m1.m2/r^2 F´ =G.m1.m2/r´^2...

How long does it take for the temperature on Earth to cool down after the sun has set? I want to know if the total solar eclipse will change the temperature.

Why is iridium plentiful in space rocks but scarce on earth?

according to f=GMm/r^2 if force changes based on a distance between 2 objects, so during free fall object is constantly changing its distance, so does that mean the Earth is exerting a non-constant force on that object? if that was right, why's that object accelerate at a constant rate of...

In the eponymous short story Lunarians have a large dome they can use to fly under their own power, using wings they rent. BUT, let's posit a person who regularly runs 26.2 marathons on Earth. Is this person fit/strong enough to actually fly in that arena? SWAGs accepted.