Earth is the third planet from the Sun and the only astronomical object known to harbor and support life. About 29.2% of Earth's surface is land consisting of continents and islands. The remaining 70.8% is covered with water, mostly by oceans, seas, gulfs, and other salt-water bodies, but also by lakes, rivers, and other freshwater, which together constitute the hydrosphere. Much of Earth's polar regions are covered in ice. Earth's outer layer is divided into several rigid tectonic plates that migrate across the surface over many millions of years, while its interior remains active with a solid iron inner core, a liquid outer core that generates Earth's magnetic field, and a convective mantle that drives plate tectonics.
Earth's atmosphere consists mostly of nitrogen and oxygen. More solar energy is received by tropical regions than polar regions and is redistributed by atmospheric and ocean circulation. Greenhouse gases also play an important role in regulating the surface temperature. A region's climate is not only determined by latitude, but also by elevation and proximity to moderating oceans, among other factors. Severe weather, such as tropical cyclones, thunderstorms, and heatwaves, occurs in most areas and greatly impacts life.
Earth's gravity interacts with other objects in space, especially the Moon, which is Earth's only natural satellite. Earth orbits around the Sun in about 365.25 days. Earth's axis of rotation is tilted with respect to its orbital plane, producing seasons on Earth. The gravitational interaction between Earth and the Moon causes tides, stabilizes Earth's orientation on its axis, and gradually slows its rotation. Earth is the densest planet in the Solar System and the largest and most massive of the four rocky planets.
According to radiometric dating estimation and other evidence, Earth formed over 4.5 billion years ago. Within the first billion years of Earth's history, life appeared in the oceans and began to affect Earth's atmosphere and surface, leading to the proliferation of anaerobic and, later, aerobic organisms. Some geological evidence indicates that life may have arisen as early as 4.1 billion years ago. Since then, the combination of Earth's distance from the Sun, physical properties, and geological history have allowed life to evolve and thrive. In the history of life on Earth, biodiversity has gone through long periods of expansion, occasionally punctuated by mass extinctions. Over 99% of all species that ever lived on Earth are extinct. Almost 8 billion humans live on Earth and depend on its biosphere and natural resources for their survival. Humans increasingly impact Earth's surface, hydrology, atmospheric processes, and other life.
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'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...
Hi.
I have been researching the Earth-Sun analemma and I found this document about deriving the Earth-Sun analemma via orthonormal coordinate systems.
Unfortunately I do not know very much about orthonormal coordinate systems and while I understand the first bit about elliptical angles, I...
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...
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...
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...
Considering artificial gravity can be created in a large enough tube orbiting an axis at a fast enough speed, consider the following:
If a spaceship is in a fixed orbit around the earth, wouldn't it be bound to Earth's axis by its gravitational pull? And if so, since the Earth rotates at...
Still in 2012 there is no reason for gravity (that i can find online) and only the few laws of gravity (Newton, Einstein). I am no Scientist and not claiming i know allot about Physics however i do know the basics and want people to put the basics aside and think outside the square on this...
Question that's been boggling my mind all day lol.. If the Earth was completely static (Not spinning around its poles, the sun, the galactic center, or moving away from the center of the universe) would time still be measurable?
Need some help with solving bet
Do spacecraft (so we're talking about powered object) have to reach escape velocity in any point of travel to leave Earth and if so, can you prove it by any scientific definition ?
This article speaks of the Earth leaving our solar systems habitable zone in a billion years or so. I would like to propose a serious discussion of what we, as a species, can do about it.
A billion years is a large amount of time, but the scope of the problem is also very large.
One...
Here's a question that I'm pretty sure I know the answer to, but I was talking with a friend earlier and it just made me second guess...
So let's say
You are a bodybuilder. One day you decide to get on your knees (in a stationary position) and try and push the Earth down. Is the amount of...