Earth Definition and 1000 Threads

Homework Statement Suppose the gravitational force of the Earth on a body was F = \frac{KMm}{r^3}. What escape velocity would a body need to escape the gravitational field of the Earth? Homework Equations v_e = \sqrt{\frac{2GM}{R}} F_g = G*\frac{m_1*m_2}{r^2} The Attempt at a...

Question: Light experiences zero time and zero distance so for a photon it must be here and there at the same instance. As the moment a photon is created it must be at position A and B at the same moment. So for a Photon it takes zero time to reach Earth from the sun. Why do we then see...

Homework Statement We can use our results for head-on elastic collisions to analyze the recoil of the Earth when a ball bounces off a wall embedded in the Earth. Suppose a professional baseball pitcher hurls a baseball (m = 160 grams) with a speed (v1 = 44 m/s) at a wall, and the ball bounces...

Dear Sirs , Could someone please tell me this. See the attached picture, is Earth orbiting Sun this way or other way around, or changes dynamically? And why does only Moon orbiting Earth while Earth doesn't orbiting the Moon? Don't they both have relative gravitational force to each other?

The thought came to my mind yesturday : does not Earth in its movement looks like pendulum tied to the Polaris ? Only the very long one - comparable to an object swinging about 1 cm circle at a tie of about 15 000 km (if my quick calculations now are correct).

I'm interested in calculating the total velocity of an object on Earth from the farthest frame of reference (the observable universe). I apologize that I am not a physics or science major so please bare with me. I've posted on another google forum and was told a few different ideas...

So I would agree that it has a uniform tangential velocity but would the centripetal acceleration of the Earth put it in a non inertial frame.

Are we just really lucky that the time it takes for Earth to orbit the sun is 365.25 days? I mean if it was something like 365.71 days, then we couldn't have our simple leap year every four years. We would have to have a 71 leap years every century, or even if we were to simplify it a bit, 7...

I would like to analyse the effects of passing a laser/microwave through the Earth's atmosphere, in relation to space-based solar power. As I can't do my experiment on the real scale. I would like to know if it's possible to scale it down. I.e. replicating the relative amounts of gas at...

So I was thinking about the equation for the acceleration of gravity on earth, or g: m*g=G*M(earth)*m/d^2 I guess it's universally accepted that different masses on Earth's gravitational acceleration is 9.8m/s^2, regardless of the mass of the object. This is because the two "m"s cancel...

Hi, I read something interesting about some amateur astronomers lasing the ISS with a blue-light laser, and the astronauts were able to spot it. How powerful would a laser have to be to be seen by the human eye from Mars? It would be shone from the dark side of Earth of course. Are we...

An asteroid is at a distance of 2 x106 km from Earth and is moving with a speed of 10 km/s. Without gravitational pull, the asteroid would miss Earth by a perpendicular distance of 25,000 km from the center of Earth. What is the closest distance between the asteroid and Earth? Does it hit...

Homework Statement Assume that the interior of the Earth is an incompressible fluid. The density is constant: ρ = M/V. The pressure p(r) depends on the distance r from the center of the earth. The equation for static equilibrium of a self-gravitating fluid sphere is p(r)δA − p(r+dr)δA −...

I read in a article that Earth revolves around the sun at speed of 30km/s but from where did it get its velocity at the beginning..?

I'm somewhere at a suburb near Sydney and I have problems designing an experiment to measure the strength of the Earth magnetic field so that means now I'm close to geographic south and I'm close to magnetic north right? how do I measure the angles between the GS and Mn and what do I have to...

Ok so this is silly and purely hypothetical... I am under the impression that should we ever decide to construct a space elevator we would need a pretty large mass on the space side of things. and that is one of the hurtles to making one. I am wondering if we have the capability to...

Lets day a day on Earth was 12 hours. How would the reduced daily temperature effect pressure systems? How would the coriolis effect be different? Would winds and storms be more or less frequent and would they generally be stronger or weaker?

Homework Statement I have an assignment that I need help with. It asks if Australia is a viable place to launch rockets from. Doesn't say what type or anything like that. I have worked out the speed of the person relative to Earth in a few different spots so I can compare. I am aware that I...

answer with full equations please and steps if you can thanks in advance 7. Shirley and Wilhelmine pin a giant salamander (50 kg) against a wall with a force of 1500 N so that it is suspended off the ground without slipping. Draw a free body diagram for this situation, write equations for...

Imagine a balloon with nothing in it except two masses M1 and M2, like first drawing. The gas of atmosphere apply a force to move up Fgas, and the weight apply a force to move down Fm1+2. Weight of M1+M2 is equal to the force from gas (opposite direction). Now, rotate M1 and M2, like that the...

Homework Statement My physics teacher today said that the Earth exerts the same amount of gravitational pull on sun;as the sun exerts on the earth. Is this really true? Homework Equations There is no equation. The Attempt at a Solution I am very confused with this. How can the...

Hi, the problem is stated as following: The Earth (mass=5.98×1024 kg) rotates around the sun in an orbit that is approximately circular, with a radius of 1.5×1011 m. Find the orbital speed of the Earth around the sun. [itеx]F=mv/r2[/itеx] I get that I need to use this equation but I'm...

I don;t really know how should I "tackle" this problem. The only thing I got is the answer for a) i) 1.9 * 10^11 J. It's a problem from IB Oxford Study Guide. http://img59.imageshack.us/img59/4986/fiz6.jpg I would be very grateful if You could help :) Thanks!

Homework Statement Calculate the relative change in the distance of the Earth from the Sun, if the mass of the Sun is 15% lower than today weight of the Sun. Suppose that the Earth moves and will move along a circular path and will maintain its angular momentum. Homework Equations...

I used this equation to find the time in seconds for the Earth to complete 1 orbit around the Sun. p=2\pi\sqrt\frac{\alpha^3}{\mu} I put in 149598261000 metres for the semi-major axis, and 1.33E+20 for the gravitational parameter. I got 3155391.8 seconds for the period. This I believe...

Homework Statement Suppose the mass of the Earth were doubled , but it kept the same density and spherical shape. How would the weight of objects at the Earh's surface change? Homework Equations Fg=Gm1m2/r^2 The Attempt at a Solution g=G2m/r^2 g=19.59817612 g/g(on Earth - 9.8)...

Lets say Earth as a moon of a gas giant. Let's say it orbited the gas giant the size of Saturn every 24 hours. I understand that the part facing away from the gas giant would have a day/night cycle like the planet Earth but what about the side facing the gas giant? Would it get any sunlight...

It appears to me that the reason that you can be shocked while contacting a high voltage line and the Earth is not because of any inherent electrical quality of the earth, but because the power grid has been connected to Earth at multiple grounding points. I have concluded that if the grid were...

Let's assume there is a hole that goes through the center of the Earth with ideal conditions (earth is spherical and gravity is the only force). If you dropped an object with a mass of, say 20kg, what is its velocity at the center of the earth? I know the force is much like that of a spring and...

Galileo tried to convince church leaders of the correctness of the Copernican Theory. He had difficulties because the leading thinkers of his day couldn't believe in the rotation of the Earth on its axis. They thought that a spinning Earth would be easily felt and the Earth must be stationary...

The L4 position is stable in the Earth Moon and I perturbing a satellite by km in the x direction to see the trajectory over the course of the year. However, the satellite isn't moving. Can anyone see if there is something wrong? I gave the satellite no initial velocity. In[2587]:=...

When I was a child, I picked a iron from the earth. It looks a iron, it has a thin layer rust outside. but the shape looks like a stone. it is about 26mm long. I erase a little rust by knife. then the position will not get rusty afterwards in the room even many years.

Somebody estimated that if cables will be extended from pole to pole and contacts placed on equator we could obtain 100.000 V, as Earth rotates in its own magnetic field.

Homework Statement (a) Given that the period of the Moon's orbit about the Earth is 27.32 days and the nearly constant distance between the center of the Earth and the center of the Moon is 3.84 \cdot 10^8 m, use T^2 = (\frac{4\pi^2}{GM_E})a^3 to calculate the mass of the Earth. (b) Why...

I'm sorry if this sounds confusing. But I'm writing this question exactly how it is written in my textbook. I am stumped on this problem: Find the potential function and gravitational field of the earth. Then use those equations to determine the work that must be done to get a 100kg satellite...

Like the title says. I"m guessing tens of thousands of years?

My professor was showing us how to calculate the Circumference of the Earth using Eratosthenes method, as shown here. I completely understand this method. http://www.bsin.k12.nm.us/Curriculum/CAP/completed%20files/astronomy/completed%20files/eratosthenescircumf.html However he told us he had...

Homework Statement If the gravitational acceleration at Earth's surface is given by: g = GMe/Re^2, show that the period of rotation of a spaceship needed to make an astronaut feel the same normal force on the ship that they would feel on Earth, when it is given by T = √[(4pi^2)(Rs)(Re^2)/GMe]...

Today an interesting question came to my mind... I have heard that when is a conjunction of planets to Earth, it affects our weight. If the conjunction occurred at larger planets to Earth - Jupiter, Saturn, Uranus, Neptune (in one line with Earth) - how it affects our weight? Surely we will...

I am trying to improve my understand of the basic elements of GR. I have read that the Earth orbits the sun because spacetime between the Earth and the sun is warped, mainly due to the sun’s mass. The Earth follows a geodesic, which is the equivalent of a straight line in curved space...

Homework Statement A spherical shell of diameter D, filled with hydrogen orbits the earth. The average intensity of solar radiation, in a plane perpendicular to the rays is 1.4kW/m^2. Calculate the total force of solar radiation pushing it off its orbit as a function of the shell's albedo...

In the galaxy carbon is on 4th place (after hydrogen, helium and oxygen) In Earth crust it has respectable 15th place. Hydrogen, helium, neon - they are on to the top galaxy popularity list, but are too light to be kept by our planet in proportional amount. Quite a few elements in Earth...

I've been reading of the (surprising) fact we are uncertain on whether there is Nuclear Fission in the center of the Earth or not (yet we know so much detail on structures at the other end of the Universe), and I wonder, was the Earth radioactive at its early stages? And if yes, would that...

If there was no earth, what would be the acceleration of gravity from here from the Sun?

Hi, This question is about a discussion in the two chief world systems, the second day about p 230 in the modern science library edition (around figures 10 and 11). I haven't found the excerpt online so I hope someone has the book. As an objection to a rotating earth, the claim that any...

My understanding is that generally with space flight, when you accelerate in the direction of orbit, you don't go around the Earth any faster but instead ascend to a higher orbital plane, which arguably has a longer period of orbit. Is there any manuver method that let's you move around the...

A question was posed that I decided to have a crack at, and I want to check my understanding. This isn't homework by the way, just trivia. Also the thread title is not really correct but I didn't want to complicate things! Here's the question: What is the relative difference in the distance...

Please ignore the UFO reference and watch for 5 seconds in the below link. One can see the shadow of Skylab on the Earth. Skylab is in a 235 mile orbit above the surface of the Earth. Clouds are about 5 miles above the surface of the Earth. So the camera capturing the images is at least 230...

Homework Statement The mass of the Moon is 7.35*10^22kg. At some point between the Earth and the Moon, the force of gravitational attraction cancels out. Calculate where this will occur, relative to Earth. Me = 5.98*10^24 kg Mm = 7.35*10^22 kg D = 3.84*10^8 m g = 6.67*10^-11 Nm^2/kg^2...

Homework Statement Determine the speed with which the Earth would have to turn to rotate on its axis so that a person on the equator would weigh 3/4 as much Homework Equations VT=r*ω ; Vi=469 m/s is tangential velocity of earth ƩF=M*ac=m*Vt^2/r The Attempt at a Solution The...