What is Escape: Definition and 372 Discussions

Atmospheric escape is the loss of planetary atmospheric gases to outer space. A number of different mechanisms can be responsible for atmospheric escape; these processes can be divided into thermal escape, non-thermal (or suprathermal) escape, and impact erosion. The relative importance of each loss process depends on the planet's escape velocity, its atmosphere composition, and its distance from its star. Escape occurs when molecular kinetic energy overcomes gravitational energy; in other words, a molecule can escape when it is moving faster than the escape velocity of its planet. Categorizing the rate of atmospheric escape in exoplanets is necessary to determining whether an atmosphere persists, and so the exoplanet's habitability and likelihood of life.

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  1. Angelos K

    Exploring Escape Peaks from Gamma Rays

    How do escape peaks occure? I mean peaks originating from a gamma ray located at the Energy value of \ E_{peak} \equiv E_{gamma}-511KeV. I read that an annihilation process takes place and one of the annihilation photons escapes detection.To arive at detecting an Energy of E_{peak} the...
  2. C

    Total Mechanical Energy & Escape Velocity: Explained

    Hi, I just had a question that why the total mechanical energy has to be zero in order for an object to achieve escape velocity? Thanks!
  3. K

    Gravity & Big Bang: Can Matter Escape Its Own Pull?

    Short question; Matter attracts matter, black holes even attracts light. If all matter in this universe was together, wouldn't that create big enough gravity to never let that matter go? Or would it create some kind of implotion? Or how could Big Bang be? (Sorry for my bad english, and maybe...
  4. P

    MATLAB How to escape a suspended Matlab?

    Hi all, I sometimes get into trouble of running Matlab programs, then when I press Ctrl+C, the program does not stop. I can only reset the PC and that takes a lot of time. Does anyone know other ways to stop a stubborn running program?.
  5. P

    Electric Potential problem escape veloctiy.

    Homework Statement http://www.phy.mtu.edu/~gagin/2200/textfiles/ph2200-ex2-f05.pdf #23Homework Equations My attempt at the equation: Vi = sqrt(2/m * ((K*1.5nC*e/.005m) + (K*1.5nC*e/.005m))) The Attempt at a Solution My equation gives me a value that is too large. Any help appreciated. I...
  6. R

    Ship Adrift: 500 m from Reef, Can It Escape?

    An oil tanker's engines have broken down, and the wind is blowing the tanker straight toward a reef at a constant speed of 1.5 m/s . When the tanker is 500 m from the reef, the wind dies down just as the engineer gets the engines going again. The rudder is stuck, so the only choice is to try...
  7. Saladsamurai

    When calculating escape speed why is v_f =0

    That's all. I am just trying to derive the reason why when using comservation of mechanical energy v_{final} goes to zero?
  8. M

    Is Additional Speed Beyond Orbital Velocity Needed for Escape?

    of course i know how to count thaht but i ve got one question. If something is moving on the orbit with velocity v, and escape velocity is u, then when we want our object to escape , the minimum speed which we must add is u-v ?
  9. J

    Minimum escape velocity of a projectile required to rise a certain height

    Homework Statement A projectile is launched from the surface of a planet (mass = M, radius = R). What minimum launch speed is required if the projectile is to rise to a height of 2R above the surface of the planet? Disregard any dissipative effects of the atmosphere. Homework Equations...
  10. F

    How cant EM wawe escape from a black hole?

    i need to have some scientific papers about this. I understand the massive ones but i can't understand it when it comes to a EM wawe. Can anyone advice me a book or a paper ?
  11. H

    Moon's Escape Point: Beyond Earth's Gravity

    What is the distance from the moon where the gravitational influence of the Earth is weaker than that of the moon? I haven't found it in any online encyclopedia and unfortunately Nasa.gov is not working for me. I would imagine it would be easy to find, but to my amazement I haven't even found a...
  12. F

    Escape velocity & Black-Body Radiation

    I'm being confused between a Physics past exam paper book and a Physics study guide. Is the escape velocity derived from EK + EP = 0 (this makes the escape velocity depend on the mass of the body to escape from i.e. Earth or a planet) or EK = EP (this makes the escape velocity depend on the...
  13. P

    Understanding Escape Velocity and Gravitational Potential Fields

    Though my question is stupid, please help me out... Why can't I get out of the gravitational potential field without the escape velocity?
  14. I

    Finding Escape Velocity from a Gravitational Potential Energy Surface

    Homework Statement By considering the gravitational potential energy of an object at the surface , find an expression for the escape speed from the surface and determine its value. Homework Equations GPE= mgh The Attempt at a Solution KE= 1/2* m * v^2 GPE= mgh GPE+ KE = 0...
  15. M

    Escape velocity and gravitational potential energy

    Hi guys...something does not seem right in physics... escape velocity is defined as the initial velocity required by a projectile to rise vertically and just escape the gravitational field of a planet and gravitational potential energy = 0 only at infinity displacement from planet (i.e...
  16. E

    What is the significance of high-speed gas particles in Earth's atmosphere?

    The Earth's atmosphere is lacking in gases like hydrogen and helium because at a given temperature, a 'significant fraction' of hydrogen or helium particles have speeds greater than Earth's escape speed, while gases like oxygen only have a 'negligible fraction' of the total number of particles...
  17. R

    What is the vector equation for escape velocity?

    hi, i have been looking for a while but stillnot managed to find a vector equation for the Escape Velocity. i know the escape velocity is: v=sqrt(2GM/r) i would like a vector form to extend a program i am making for a three body gravitational problem many thanks richard
  18. J

    Why can gravity escape a brane?

    According to the things I've been reading, while most forces and particles can be trapped on a brane, gravity can escape it and thus provide a means of interaction with other branes and the bulk. The reasoning given is that since gravity is woven into spacetime and has a component in the...
  19. B

    Escape Velocity and Short-Distance Space Travel: Understanding the Science

    can someone please help: i know escape velocity is the velocity you need to give an object for it exit the pull of the Earth and travel an infinite distance away from earth. now let's say you have a space shuttle that you need to take to Mars or the moon or something. why would you need to...
  20. T

    Escape the Stilted Room: A Rope Climbing Challenge

    You are locked in a 50'x50'x50' room which is on 100' stilts. There is a small window near the floor on one side (too far from the stilts to reach), with a small hook embedded in the floor beside it. In the centre of the room hanging from the ceiling are two 50' ropes. You have no tools...
  21. K

    Escape Velocity from a Black Hole's Gravity

    Homework Statement A black hole has a mass of 2x10^31 kg What is the minimum radius from which a photon can escape its gravity? Homework Equations The Attempt at a Solution does this equation give me the answer "gravitational radius" = (2Gm)/c^2
  22. L

    Minimum energy required to escape the grav field

    Homework Statement When it orbited the Moon, the Apollo 11 spacecraft 's mass was 13400 kg, and its mean distance from the Moon's center was 2.56393 X 10^6 m. Assume its orbit was circular and the Moon to be a unform sphere of mass 7.36 X 10^22 kg. a) Given the gravitational constant G is...
  23. T

    Can a Baseball Reach Escape Velocity?

    I have a rather simple question for the minds who paruse this forum. My question is this. Can a baseball thrown overhand by a human being by provided with enough backspin for it to escape it's initial velocity vector, and in fact actually rise as it approaches the plate?Thank you,Tim.
  24. MathematicalPhysicist

    Escape velocity of a body from a black hole.

    i read that the escape velocity from black hole is greater then C, my question is: is that true for all black holes, or we could have some black holes which have smaller escape velocity than C, there's the equation v=sqrt(2MG/R) which implies that M/R>c^2/2G, but does the star before it becomes...
  25. G

    Confirming Convection: Heat Escape Through Unlidded Containers

    Hi, Just a quick question, I just want to check that i am on the right lines! When heat escapes through the top of a container which does not have a lid, is that due to convection? i/e hot air is less dense than cold air, so rises. Cheers o:) Gemma o:)
  26. S

    Why doesnt a photon escape from a black hole?

    Explain why elight emitted at a point inside the Scwarzschild radius (r<a) cannot be seen by a distant observer. (by one at r-> infinity) well we know the trajectory of a photon is given by \dot{r}^2 = c^2 \lambda^2 - \left( 1 - \frac{a}{r}\right) \frac{J^2}{r^2} where J repsents the...
  27. -Job-

    How does a body escape its gravitational field?

    Might seem like a strange question, but why does the Earth move? Shouldn't it's gravitational field keep it in place? Wouldn't the space immediatly surrounding the Earth offer considerable resistance to its movement? Things on the surface of the planet have a hard time escaping the Earth's...
  28. Astronuc

    News A Girl's Escape from Cruelty: Gulsoma's Story

    This story is very disturbing and sends me into a rage! Abuse of children and women is wholly inappropriate and unacceptable - period! from Hotzones by Kevin Sites http://hotzone.yahoo.com/b/hotzone/blogs2986 I do not want to hear rhetoric from the US government that Afghanistan is on...
  29. M

    Calculating Escape Speed, Lagrange Points, & Stress/Strain of Rope

    1: Determine the escape speed of a rocket on the far side of Ganymede, the largest of Jupiter's moons. The radius of Ganymede is 2.64 X 10^6m, and its mass is 1.495 X 10^23 kg. The mass of Jupiter is 1.90 x 10^27 kg, and the distance between Jupiter and Ganymede is 1.071 X 10^9m. Be sure to...
  30. S

    Why Is Zero the Upper Limit in Escape Velocity Derivation?

    escape velocity derivation The problem is thus: The acceleration of a satellite is given by -gR^2/r^2 where R= radius of Earth and r = distance of satellite from center of the earth. Find escape velocity. Now I have read the solution to this problem and in it the author at one point has...
  31. J

    Does the universe need an escape velocity?

    The question is, Does the universe (the conglomeration of all energy in existence) logically require an escape velocity? My reasoning is thus. If the universe is at least partially composed of massive objects that exert gravitational pull, wouldn't the sum of every massive object in the...
  32. E

    Isn't escape velocity against classical physics?

    "In physics, for a given gravitational field and a given position, the escape velocity is the minimum speed an object without propulsion, at that position, needs to have to move away indefinitely from the source of the field, as opposed to falling back or staying in an orbit within a bounded...
  33. M

    Escape Velocity: How Does It Affect Objects of Different Masses?

    I keep reading that escape velocity from the Earth is about 7 miles per second or 25,000 miles an hour... I know escape velocity is determined by the size of the object with the gravitational pull (earth) and how far away you are from the center. What I can't seem to understand is how 2 objects...
  34. A

    Possible method to escape a black hole?

    What's wrong with the following method of escaping from inside an event horizon (and possibly exploring physics inside it?) 1. A rocket with a very strong engine slips below the event horizon -- just barely. 2. Fire the rocket engine so it would travel at c-epsilon were it not for the...
  35. JasonJo

    Can I Escape Poverty with a PhD in Mathematics?

    Hey guys, I am wondering if any of you are unfortunately in my situation and are poor. My parents barely scrape by and my brother is currently going to grad school for his MBA, so he won't be able to help out for another 3.5 years. my parents are about 58 years old. It saddens me that they...
  36. N

    Calculating Escape Velocity for Reaching Altitude of 800km

    Q: In the absenceof air resistance, the least speed with which a body must be projected vertically upward from the Earth's surface if it is to reach an altitude of 800km is... 800km = 8.00x10^5 m radius of Earth = 6.37x10^6 m mass of Earth = 5.99x10^24 kg Kf +Uf = Ki + Ui 0 + 0 = 1/2...
  37. Z

    Escape Speed Calculation for Identical Planets

    the question is : there are two identical planets of mass M and radius R spaced 6R apart. What is the escape speed of a rocket launched from the mid-point (3R) between two planets? I use the energe conservation law. K1 + Ua1 + Ub1 =K2 + Ua2 + Ub2 = 0 to get the Vi because the rocket is in...
  38. S

    Projectile Motion: Escape Velocity and Altitude at 55%

    Question 1: If a projectile is launched from Earth with a speed equal to the escape speed, how high above the Earth's surface is it when its speed is 96% of the escape speed? On this question i understand i am not finding how high it would go if it were launched at 96% of the escape velocity...
  39. S

    Escape Velocity of a spherical asteroid

    Consider a spherical asteroid with a radius of 5 km and a mass of 8.65x10^15 kg. (a) What is the acceleration of gravity on the surface of this asteroid? ANSWER: ___ m/s2 (b) Suppose the asteroid spins about an axis through its center, like the Earth, with an angular speed . What is the...
  40. R

    G:"Solving Orbital Geometry: Achieve Escape Velocity & Orbit Free Return

    Unless you have orbital geometry down cold this might take a little thinking. SET UP A large independent planet with a thick atmosphere included is 100 Mega-meters in diameter. Beyond that diameter we can consider that we have a real vacuum outside that diameter. “Independent” only means...
  41. Z

    Exploring GR Effects on Escape Velocity of a Star & a Black Hole

    This is an analysis involving general relativity (GR). Let a spherically symmetric, uncharged, nonrotating star (not a black hole—that comes later) have an escape velocity = infinitesimally less than c at its surface. Then its r-coordinate radius (also known as the reduced circumference and...
  42. T

    Universal Gravitation on escape velocity

    On dealing with Universal Gravitation topic, I came across this question: what is the min speed, relative to the sun, necessary for a spacecraft to escape the solar system if it starts at the Earth's orbit? My working: v=sqrt(2GM/R), where G=universal constant, R= distance between Earth...
  43. C

    Understanding 'Escape Velocity' - Debunking Misconceptions

    Why do people always use the misleading term 'escape velocity'? If I had a rocket whose engines provided a thrust of 1N more than its weight (thus yielding a miniscule net force up), i would be able to go to Mars with it, given the required amount of time, right? Thrust > Weight, so it...
  44. S

    How does escape velocity vary with an object's mass?

    another simple question: what is the energy needed to move an object away from the planets gravitational field at CONSTANT speed? 1) Ep 2)Ek 3)Change in Ep 4)Change in Ek
  45. P

    Light in a Black Hole: Does It Escape or Lose Energy?

    I've asked this before, but received no response. What happens to light "trying to escape" from a black hole? Does it lose all its energy? Does the light leaving the sun lose some of its energy as it goes "uphill" the geometry of spacetime? And as E=hf, does this mean that the light shifts...
  46. H

    Escape Speed for Solar System Probe

    QUESTION: A space station orbits the sun at the same distance as the Earth but on the opposite side of the sun. A small probe is fired away from the station. What minimum speed (m/s) does the probe need to escape the solar system? MY UNDERSTANDING AND SOLUTION: The escape speed v from a...
  47. B

    Escape Velocity Given Radius of 2 Objects

    Got a dosie of a problem I need checked. I've been playing around with this problem, and after I submit the right answer (the ans. I got) , it came out wrong. Someone tell me what I'm doing wrong PLEASE thanks: The prob. is to calculate escape velocity from a white dwarf and a neutron...
  48. S

    Comparing escape velocities on Earth and Mars

    The problem is.. the mass of MArs is 0.107 times Earth's mass and its raduis is 0.532 times Earth's raduis. how does the escape velocity on Mars compare to the velocity on Earth? i did this.. Vof escape = square root of 2G M(mars)/r(Mars) Vof escape is proportional to the square root of...
  49. I

    Impossible escape velocity question

    I've got a question in front of me that asks to find the escape velocity for a hypothetical celestial object that has the same density as the sun. MC answers are - 1)2.51 x 10^3 m/s 2)6.18 x 10^5 m/s 3)3.08 x 10^5 m/s 4)5.42 x 10^10 m/s As far as I can work out its not possible to find...
  50. M

    How do Gravitons escape from a Black Hole?

    1 : Am I right in thinking gravitons are the mediators of the gravitational force, just as photons are the mediators of the electrostatic force? If this is correct, then presumably the gravitational force between A and B can only be manifest (detected) in circumstances where gravitons can...
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