Earth Definition and 1000 Threads

I'm working on a potential sci-fi story that takes place on a post-apocalyptic Earth. The idea is Something Horrible 1A happens, then, 15-20 years later, Something Horrible 1B comes to finish us off. In a perfect world, the Moon is gone after 1A. Initial possibilities included a long orbit...

Homework Statement In a particular region of the Earth's atmosphere, the electric field above the Earth's surface has been measured to be 148 N/C downward at an altitude of 260 m and 165 N/C downward at an altitude of 410 m. Calculate the volume charge density of the atmosphere, assuming it to...

The sun radiates its energy in all directions by emitting photons. As the photons travel as electromagnetic waves it reaches the earth. The photons collide with atoms and molecules in the atmosphere due the collision the energy of photons are emitted as heat. The atmosphere is thus heated and it...

Homework Statement This is a problem I picked for my calculus one class that I would like to solve, then model the solution using the sandbox video game universe sandbox. I would like to calculate the closest stable orbit of the moon, if possible allowing for some eccentricity in the orbit...

Is the the force that keeps the Earth spinning the same force that moves the moon farther away from us? Spinning objects are accelerating and it takes a force to accelerate an object so the force that keeps the Earth spinning is centrifugal force right?

Homework Statement I don't want to post the actual question because I want to understand the situation in a general case. Basically, there is a bullet that moves south along the surface of the Earth as in this diagram: http://abyss.uoregon.edu/~js/images/coriolis_effect.gif. You have to find...

Homework Statement Suppose we had a straight tunnel, through Earth's center, to a point on the opposite side of the planet, and used it to deliver mail to the other side. With what speed would our packages pass through Earth's center. Homework Equations ag = (GM)/R2 Mins = (4/3)πR3*ρ The...

Hi, I'm trying to measure the electric field of the Earth using a simple set up and would just like some opinions on the viability and practicality of this method. The set up is as follows, two parallel metal plates with one larger than the other, the larger one is placed over the smaller at a...

...would I have to be so I spend 75% of the time in the dark as the Earth spins? Imagine the sun shines on the Earth in such a way that it casts a shadow that is at 60 degrees to the axis of the spin of the Earth (Assume the Earth's axis is 0 degrees) as shown in my diagram below. I am trying...

Question: Muons created in the upper atmosphere are sometimes able to reach the Earth's surface. Imagine that one such muon travels the 60km from the upper atmosphere to the ground (in the Earth's frame) in one muon half-life of 1.52us (in the muon's frame). How thick is that part of the Earth's...

Is there any portable/small device that will allow me to measure the strength of the electron field emanating from the Earth's surface, i.e., the ground at a given location? Thanks!

Homework Statement There exists a spaceship orbiting between the Moon and the Earth. Find the perfect spot where the gravity due to Earth is equal to the one caused by the Moon. I have already solved for the ratio ## \frac {R_E}{\sqrt{M_E}} = \frac {R_M}{\sqrt{M_M}} ##. ## R_E ## is the...

Assume that the Earth is spherical and recall that latitudes range from 0° at the Equator to 90° N at the North Pole. Consider Dubuque, Iowa (42.50° N latitude), and Guatemala City (14.62° N latitude). The two cities lie on approximately the same longitude. Do not neglect the curvature of the...

Homework Statement The Earth's distance from the sun varies from 1.471 x 108 km to 1.521 x 108 km during the year. Determine the difference in (a) the potential energy, (b) the earth's kinetic energy, and (c) the total energy between these extreme points. Take the sun to be at rest. Homework...

Chemists claim to have solved riddle of how life began on Earth http://phys.org/news/2015-03-chemists-riddle-life-began-earth.html Here is the journal article http://www.nature.com/nchem/journal/vaop/ncurrent/full/nchem.2202.html

Homework Statement Suppose that some time in the future we decide to tap the moon's rotational energy for use on earth. In additional to the astronomical data in Appendix F in the textbook, you may need to know that the moon spins on its axis once every 27.3 days. Assume that the moon is...

If gravity is the effect of spacetime curvature, then why is it stronger on Earth than the moon? In other words, it is the curvature of space and time that gives the effect of pulling an object towards a larger object, so once that direction of pull is established why would the size of the...

Will the Earth's rotation someday be synchronized with its revolution around the Sun (one rotation on the axis per revolution), such as the Moon around the Earth? If not, why?

At about 05.30, Dr. Lewin makes a small calculation to find the centripetal acceleration one experiences due to Earth's spin (at the equator). He then says that because of how small the magnitude of this acceleration is, we could consider the Earth's surface to be an inertial reference frame...

Can a person suspended in space with nothing to push off of, turn themselves around?

The second law of thermodynamics say that we could harness thermal energy only if there is temperature difference between a two bodies. Will it work if we have a forcible heat rejection from one body to another? Difference of temperatures between the oceans and the outer space is around 300 K...

I was sitting down thinking yesterday, I know that it was worked out through the ages by various methods. But how did we come to the value which we have today? All I can seem to find on the subject is this https://heasarc.gsfc.nasa.gov/docs/cosmic/earth_info.html which says that it is determined...

Hi, I understand that if a ball is dropped on Earth and dropped on mars, the ball will reach the same height on both planets thanks the law of conservation of energy. Can anyone prove this mathematically? Thanks in advance

Gravity is weaker on equator. What I know, this effect is due to combination of two factors: 1. Earth is rotating with surface speed 450 m/s on equator and this is causing centripetal force which is decreasing gravity. 2. Earth is flattered on poles, so that means that there is longer distance...

If an entire system was floating wrt Earth via infinite impedance and a person (grounded) touches a conductor am I right in saying nothing would happen due to the fact there is no return path through earth? Presumably the only way to detect an Earth fault in this case is to measure the...

Impact: Earth! A meteor/comet impact simulator(text only) provided by Purdue University. Lots of fun. :smile: You can smash things into the Earth varying the diameter, density, velocity, angle, land or water entry, and your distance from impact. 1 meter: very boring. happens every 1.1 year...

Greetings !New to the forums. Here expanding my concept of what AC Electricity is My question (correct me if wrong).. If AC power alternates between +,- at a rate of 60Hertz/second and negative is used as -earth- at the AC generator If the hot wire touches the ground would happen? (I think...

Bodies in orbit around the Earth are, as I understand it, weightless. Suppose, then, that by some unimaginable process the Earth expanded to a radius equivalent to the orbital radius of a geostationary satellite, but retained the same mass. Does that imply that a body lying on the equator of the...

Good Day everyone! :wink: I don't know if this thread is repeated already. Because I can't find one. I just want to ask you guys what are your insights for the asteroid apophis' possible impact to Earth by 2029? Upon its discovery in 2004, Apophis was briefly estimated to have a 2.7% chance of...

I was just reading about the barycenter of bodies in space. My question might not make sense but, if we sent hundreds of thousands (or millions) of spacecraft to the moon filled with dirt and rocks could we change the barycenter enough for the Earth to orbit the moon? I know this is a huge...

I'll start by saying that there are a number of other sub forums that this would be applicable to, but this seems the most appropriate. I'm a engineer by trade, but I've been doing some creative writing lately, and for an idea I'm working on I'd like to hit my hypothetical Earth with a gamma...

Homework Statement R = 4000mi phi = 60 Me = 5.972E24 kg Mm = 5.972E16 kg distance of procession = 100 mi Homework Equations I know the answer is supposed to be ~1010 years. I also know what I am trying to do is have that e3 axis be pointing straight up, then when the mountain is placed on...

Homework Statement The force of attraction on an object below Earth's surface is directly proportional to it's distance from Earth's center.Find the work done in moving a weight of ##w## lb located ##a## miles below Earth's surface up to the surface itself. Assume Earth's radius is a constant...

We all know the confusion between Mass and Weight, from the language barrier. Would I be correct to say that: On Earth Bathroom weigh scales = 100kg. Mass therefore is 100kg. Weight = 981N On the Moon Bathroom weigh scales = 16.7kg. Mass is still 100kg. Weight = 167N In Space, (away from any...

Homework Statement Homework Equations The Attempt at a Solution For starters, I am a bit confused about how to work on this problem considering the only relevant equations given for this problem (in the chapter we are currently in) are the two equations for Fr and Fφ for a 2-D polar...

Homework Statement The presence of a huge ice sheet helps support itself by changing the amount of energy the Earth receives.Question 13 options: True False Homework Equations none The Attempt at a Solution Ice sheets have high albedo, therefore Earth gets less solar energy?

Homework Statement Which has the most intense sunlight hitting it?Question 2 options: A point on the Equator at sunset The North Pole at Noon on the Summer Solstace Montreal at Noon on the Spring Equinox The South Pole on the (Northern hemisphere) Summer SolstaceHomework Equations none The...

The Earth wire carries current to the ground and we walk on the ground and the ground is a good conductor of electricity. So when we walk on the ground then how come we don't feel the current from the Earth wire?

How ozone having higher molecular mass then oxygen and CO2 is on a certain upper level of atmosphere? Doesn't the more dense objects come closer to ground by gravitation?

Escape velocity is an estimate of the launch velocity of a spacecraft (without any propulsion) to overcome a planet system's gravitational pull in order to escape to ``infinity''. In this problem we consider both the gravitational attraction of the Earth and Sun (but ignoring the effects of...

My understanding is that for space shuttle to escape Earth it needs to travel at a certain high velocity. So, what happens to the space shuttle if it doesn't reach the escape velocity at edge of Earth's atmosphere to space? The question I'm asking and the answer I'm seeking is something like...

An object stand in the height 500km from the surface of the Earth. What velocity should it have to become an Earth satellite?

Homework Statement An object stand in the height 500km from the surface of the Earth. What velocity should it have to become an Earth satellite? Homework Equations a=v2/r The Attempt at a Solution v2=a*r=6,9*107=>x=8306m/S , but the solution is 7600m/S

Homework Statement A particle is dropped from a height equal to the radius of the Earth into a tunnel dug through the Earth along one of the diameters. Which of the following is/are true-- (A) Particle will oscillate through the Earth to a height R on both sides (B) Particle will execute simple...

Homework Statement 1)Find the gravitational force between then sun (2*10^30 kg) and the Earth (5.97*10^24 kg). Earths distance from the sun is 1.5 * 10^11m. 2) find the distance between a 5 kg object and a 10kg object if their gravitational force is 1*10^-4N. Homework Equations Fg=...

Homework Statement (a) Find the proper time in the rest frame of particle (b) Find the proper time in the laboratory frame (c) Find the proper time in a photon that travels from A to B in time P Homework EquationsThe Attempt at a Solution Part(a) [/B] The metric is given by: ds^2 =...

On youtube, I came across to one of many videos trying to explain General Relativity. One of the comments was interesting to me: "I understand how gravity causes an object with velocity to go in curves or to orbit, due to the curvature of space-time: the object thinks that it's traveling in a...

I wasn't sure whether to post this here or in the 'homework' section... technically it is not a homework question, but I will be happy to move it... I am really struggling with this circuit: :'( At the moment, I have no clue what to do for part i). I am sure that I will get part ii)...

Homework Statement Hello the text is in swedish but ill try my best to translate, What it says is: Determine the resultant force on the moon with regard to thr gravitation force from the sun and the Earth when it's in this position shown in the figure [ picture http://m.imgur.com/AfJOVZo ] J...

Homework Statement A 1,000 kg satellite traveling at speed "v" maintains an orbit of radius, "R" around the earth. What should be its speed if it is to develop a new orbit of radius "4R" ? Homework Equations Gravitational force equation (F) = (Gmems)/r^2 G (universal gravitational constant) =...