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.
I have completed a few chapters.
I am writing a story about a couple on New Earth which is this planet that is not 4.5 billion years old but still habitable by all Earth species. Right now in my story they have made some cow's milk cheeses and butter and they have a child but they want some...
...and to a larger extent, the mainstream environmentalist movement.
Here's an article on CNN.com, with one author being the founder of Earth Day and the other I can't identify (no bio provided for either):
http://www.cnn.com/2014/04/22/opinion/hayes-denman-solar-power/index.html?hpt=hp_bn7...
Hi, I am writing a sci-fi comic and would need an info, which is very similar to this thread:
https://www.physicsforums.com/showthread.php?p=4724396#post4724396
My question is, how much would it take for an asteroid to reach Earth after detection? A cca 'from to' range would be sufficient...
In 1889 and 1909 Roberto Mantovani published a hypothesis of Earth expansion and continental drift. He assumed that a closed continent covered the entire surface of a smaller Earth. He believed thermal expansion led to volcanic activity, which broke the big continent into smaller continents. The...
Hi guys. Consider the mean occupation number and specific intensity of the CMB photons in the CMB frame as given by the blackbody formulas: ##\eta = \frac{1}{e^{h\nu/k_{B}T_0} - 1}## and ##I_{\nu} =\frac{2h\nu^3}{e^{h\nu/k_{B}T_0} - 1}## with ##T_0## the thermal bath temperature in the CMB...
Homework Statement
The mass of the Earth is Me and the mass of the Moon is Mm. The (center to center) Earth to moon distance is d.
a) If a space probe is sent directly from the Earth to the moon, how far from the center of the Earth would the net gravitational force (due to the Earth and...
I read that the level of oxygen in the atmosphere reached its highest concentration during the Carboniferous period, with over 32% of the atmosphere by volume as O2. I was wondering, how is this measured?
The reference on wiki only links to a graph with no other content.
Thanks.
... regardless of any possible technical problems, and then, on earth:
a) someone throws an object in the air and it falls
b) someone puts an object to float in a magnetic field generated by an artificial magnet that lays on earth
In situation A I think the weight measured would...
Homework Statement
See attachment
Homework Equations
See attachments
The Attempt at a Solution
I'm really struggling to understand how to solve this problem.
I guess I need to know the volume and surface of the sea on earth?
But I'm honesty a bit lost as we don't have a...
I'm trying to get a basic understanding of Earth's origins in order to teach an advanced oceanography course to high school students this summer. The course starts with one lecture on the origins of the universe, solar system, the earth, and the ocean. Why did Earth lose its first atmosphere...
Homework Statement
Suppose that, suddendly, the gravitational attraction between the Earht and the Sun goes away.
How many time will the Earth require to reach an orbital distance from the Sun equal to the actual orbital radius of Pluto?
(Sun-Earth: 150*10^6 km; Sun-Pluto: 5900*10^6 km...
Current passes through us if we hold a conductor barefoot and it goes inside the earth. What happens next? What happens with that charge as it enters the ground? Does it combine with the cations present in the soil?
I need help understanding a certain problem. It basically stated: an airplane accumulated a positive charge, heading westward above the equator. Find the direction of the force (using the lame right hand rule thing).
The problem I had was figuring out was whether the magnetic field would hit...
Hello,
My question is regarding effect of sun's gravity on earth. I want to know that if sun's gravity can change Earth's landscape in long duration (i.e. billion of years ) or not?? Means if Earth is dead planet and all other planets are not present in the solar system and Earth is as near...
The period of a satellite revolving around the Earth earth at surface height is equal to the period of any mass thrown through a hole of the earth(which gains a simple harmonic motion)...
It seemed really interesting to me...
Why both of these periods are same?
T=2 π √(R/g)
Homework Statement
A satellite will crash int the Earth if its velocity:
stays constant
increases dramatically
decreases dramatically
Answer: decreases dramatically.??
Homework Statement
The acceleration due to gravity on the surface of the Earth is:
constantly changing
the same as on the moon
basically constant
Answer: Basically constant?
The gravity on Earth doesn't really change much day to day.
Homework Statement
If Earth stops rotating Sun suddenly , how long would it take for Earth to collide with Sun ?
G = gravitational constant
m_s = 2e30kg
m_e = 6e24kg
where m_s is the mass of the sun and m_e , mass of earth
x = 1au =1.5e11m
2. The attempt at a solution
Gravitational...
The three main effects of SR occur in inertial frames and change the description of space-time relative to a particular observer. My question here is how do these effects occur on Earth, since we know that motion on Earth is non-inertial. I know that we travel at small speeds and that we can't...
I'm trying to understand why a superdeformed nucleus may be represented as bulging perpendicular to the axis of rotation, and I'm guessing this is akin to why the Earth does so too. I've gone through secondary school and 3 years of University to have professors/teachers snigger every time they...
Why does air on Earth float? Obviously, lighter gases such as Helium and even hot air will float due to having a lowed density than the air around it. Why is it though that the base higher density gases that we breath float rather than sink to the ground? My belief is that gravity is simply too...
Why are the nearest stars to Earth mainly red dwarfs? When inspecting a list of approx. the 12 brightest stars vs. the nearest stars I see clear differences in luminosity. Again, what explains why these lists are so different in terms of spectral type?! Does it have to do with the amount of...
Hello,
I was wondering that I'm a astronaut on Moon and I thought about a one question...
If I look at the Earth (in "full moon") from the Moon, what magnitude will have the Earth? Ok, I know some typical values that the magnitude of Moon from Earth is -13 mag and the magnitude of Sun from...
I attatch a rope of a constant density to the Moon and fasten it down to the surface. I set the other end in space right above Earth's atmosphere. The angular speed of the entire rope is brought up to the same angular speed as the Moon at time=0.
http://i.imgur.com/kHlVvnM.png
What would...
Assume Earth's radius R and there is a mass m. We put that mass in height of R from the Earth's surface. I want to calculate it's potential energy.
I calculated it and got mgR/4 but my teacher said the answer is mgR/2 . Why my answer is wrong?
I just calculated the gravity in the height of R...
Hey guys,
I am trying to create a 2d simulation of the Earth going around the sun. However I am facing an issue. I am not sure what are the forces that apply on the Earth in a 2d aspect.
I know there is the gravitational pull GM1M2/R^2.
I know there is momentum, which is P = V * R...
Hello there,
I was taught:
a = {v^2 \over R}. I substitute v for the speed of the rotating Earth at the equator, and the radius, R = 6378m. And I get a = 0.03 \rm m/s^2.
It looks like the equation a = {v^2 \over R} may incorrect. Why am I taught this equation in University if it is false...
Homework Statement
Find the surface area of the Earth (as a fraction of the total surface of the earth) that lies above 50 degrees latitude North.
Homework Equations
$$A = \int_R\sqrt{|\det(g)|}d\theta d\phi$$
The Attempt at a Solution
Hence I get
$$\int_0^{360}...
Homework Statement
Would the horizontal distance traveled by a projectile on Earth be the same as one on the moon? I feel like the distances would be different, but when I was calculating the initial velocity of the projectile on the moon I used the same x value(distance) that I did for...
I have been wondering what to expect if there was a hole,
from pole to pole, that inside which we could measure the
Einstein red and blue shifts due to gravity. At first, I suspect
a blue-shift as light travels from the surface of the Earth to
the center; just less and less as the center is...
So I was just thinking about what would happen if the Earth stopped rotating on it's axis. Everything unattached would be thrown into the air. The questions been bugging me for a while, how would you calculate the air resistance on objects thrown into the air? All I have to go on is that the...
Homework Statement
The Earth's radius is 6370 km . There is a downward-pointing electric field in the atmosphere above the Earth's surface, of average magnitude 140. N/C .
a) What is the flux of the electric field out of the Earth?
b) What is the charge on the Earth?
Homework...
Homework Statement
At a certain instant, the earth, the moon, and a stationary 1030kg spacecraft lie at the vertices of an equilateral triangle whose sides are 3.84×10^5km in length.
Find the magnitude of the net gravitational force exerted on the spacecraft by the Earth and moon.Homework...
I was watching a documentary that examines what happens if the Earth slowed to a halt in the span of 5 years.
One point they didn't cover was that since the Earth is slowing down at a greatly accelerated pace, what would the people feel? How much apparent force would they feel acting on them?
Given an example of a rifle bullet traveling east or west, why does the bullet deviates HORIZONTALLY? (right on the northern hemisphere, left on the southern hemisphere)
As rotation speed in the same latitude coordinates stays roughly the same, I wouldn't expect the bullet, or any other...
Homework Statement
A car drives north at 40mi/h for 10mins then turns east and goes 5min at 60mi/hr. Finally it goes southwest at 30mi/h for 6min.
a) determine the displacement
b)average velocity for this trip
The Attempt at a Solution
x-component: 60mi/hr/60min x 5min = 5mi...
Object with positive mechanical energy in an attractive force field moves along a hyperbolic path and whose energy is zero, moves along parabolic path...isn't it?...But why?...Can't any object with ve energy move along the line joining centre of force?...If its radial component of kinetic...
Newton showed that F=G(m1m2)/r2
When calculating the force of gravity on the surface of the Earth, why do we use the radius of the Earth for our r value? Of course, the above Newtonian equation suggests we should, but it seems rather counter-intuitive.
I must admit to not having taken a...
From Earth with the naked eye, the Moon is pretty small. If a nuclear weapon were detonated on the Moon, would it be visible from Earth? Would it make a difference if the device were detonated during local daytime (in full sunlight) as far as visibility is concerned?
If it makes a...
1) What would happen if artificial satellites in various orbits above the Earth exploded? Where would the fragments go?
2) How do constituents of asteroid belts stay in their orbit? Why don't they change orbits? Why that particular distance?
Thanks
I'm doing a research paper based on mining asteroids or near Earth objects.
I was wondering, could we pull/move a relatively large asteroid About half as large as the moon could we use is as an anchor to launch missions?
Thanks!
For the sake of this challenge, you can assume that the world behaves nicely (everything is continuous, differentiable etc, the world is a sphere blah blah blah) but figurative bonus points if you assume fewer things. If you're looking for an easier challenge check out Challenge 10a.
The...
For the sake of this challenge, you can assume that the world behaves nicely (everything is continuous, differentiable etc, the world is a sphere blah blah blah) but figurative bonus points if you assume fewer things. If you're looking for a bigger challenge check out Challenge 10b.
The...
Hi,
I'm sure this topic has come up before, however, it was always under the requirements of being realistic, i.e. taking drag, air resistance, Earth rotation and what not into account. Also, I couldn't find any equations so that I can do the math myself. Hence, here is my question...
I understand there are two factors: the gravitational forces from the sun and the moon and rotation. Rotation has a greater effect than the gravitational forces, so rotation is what I'd like to focus on.
When the Earth spins, a centripetal force acts on the Earth's crust and points to the core...
Hello, everyone :-)
We have a wooden sphere at a height of h = 1 m above the surface of the Earth which has a perimeter of RZ = 6 378 km and a weight of MZ = 5.97 · 10^24 kg. The sphere has a perimeter of r = 1 cm and is made of a wood which has the density of ρ = 550 kg·m − 3. Assume that...
Lets say Earth lost its magnetic field 4 billion years ago and lacked geological activity like mars. Would the atmosphere of Earth be comparable to Mars atmosphere? How thin could it have been without a magnetic field and constant geological activity? Thank you.