Earth Definition and 1000 Threads

Hello, Can someone please explain to me how Astronauts in Low Earth Orbit do not instantly fry up when in direct sunlight? How does the International Space station, for example, not become a torch-lit super-oven when the sun's rays hit its walls? Thank you for helping me understand, and...

Does gravity on Earth stays constant regardless of height?. For instance, if a person standing at a mountain would he experiences the same gravity as the person standing on the ground?

Homework Statement The Earth is slightly thicker around the equator and hence $I_{0}\neq I_{\zeta}$ I am curious in finding the angular velocity for the **precession** between using the fact that the distance between the spin axis and the precession axis is 10 meters on the surface of earth...

All sources I have found on the web give the abundance of the elements on Earth measured by weight. By that oxygen is number one or iron, depending on where you look. But when counting just the number of atoms wouldn't that make hydrogen number one? thanks

Water is incredible. We see lakes of hydrocarbons on Titan and they remind us of water lakes on Earth, so we postulate that an entirely difference sort of life might thrive there. But do liquid hydrocarbons really have what it takes to do all the things that water does? Here's my question...

Why is separation of Earth and sky so common in different mythologies around the world? EDIT: Sorry about my poor phrasing of the question. My question is actually why people would assume Earth and sky were joined once. Which observation/ reasoning led them to make up such a non-obvious story...

Hello. My name is Andrew Huerta and I am a comic creator. I am currently doing some research for a comic I'm working on and I'm having a bit of trouble grasping some of the concepts I've created. Basically, what would be the reality of this situation? Like, what would that scenario do...

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?

how does U 238 change to U 235 in nature earth or how does uranium enrichment in nature

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...

Fantastic infographic! http://lightsinthedark.files.wordpress.com/2013/04/50-facts-about-earth3.jpg

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...

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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