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. N

    Photon "escaping" from photon sphere in Schwarzchild space

    Homework Statement Close to a Schwarzschild black hole, a photon is emitted between r = 2(mu) and 3(mu), where \mu = \frac{GM}{c^2} . The photon is emitted at an angle (alpha) to the radial direction. At r = 2(mu), the highest angle that the photon can escape at is (alpha) = 0; at r = 3(mu)...
  2. H

    Escape from gravitational field

    1. A satellite is revolving very close to earth. what is the % increases in velocity needed to escape from the gravitational field of earthHomework Equations v= root gh The Attempt at a Solution Sorry, i don't have any solution .
  3. D

    Escaping earth's atmosphere with a balloon

    Hi all, So my question is, could you use a weather balloon to assist with escaping the atmosphere and attaching a rocket to take it the rest of the way, and we're talking a really small payload obviously. Would the weight of the fuel/rocket weigh down the balloon enough to significantly...
  4. Zack Davis

    Escape Velocity and Gravitational Force

    Hey Guys! I've been doing a few equations in regards to planetary escape velocity and gravitational force. The below links have the escape velocity of listed planet on the left side of the board, the gravitational force between the Sun and given planet on the right side. In the middle of the...
  5. Zack Davis

    What is Saturn's Escape Velocity and How Do I Calculate It?

    Hey guys and girls. I've been trying to calculate Saturn's Escape Velocity but my answer is coming out way to high. Could someone demonstrate how I would go about finding Saturn's Escape Velocity?
  6. S

    Time dilation on the surface of a planet and escape velocity time dilation

    If an object falls through a planet's entire grav. field, before impact it's velocity will be the escape velocity. I assume the time dilation for an observer on the object will be the same as for an observer on the planet. They're not added together. Another point - since time dilation on a...
  7. B

    Confused on escape velocity derivation

    I'm confused on how you get the formula v=root(2GM/R²). I know you can use work=forcexdisplacement (W=Fd) so F=W/d. W=½mv² and R=d. Hence, F=½mv²/R Equate that to F=GmM/R² and rearrange to get v=root(2GM/R²). That makes sense as it involves the kinetic energy needed/work done in reaching orbit...
  8. C

    Escape velocity of an Earth-Moon system

    Homework Statement What velocity is required to escape from the Earth-Moon system from the surface of the Moon? Assume that all of the necessary velocity is imparted at once, as with a cannon or rail gun on the Moon itself. In what direction must the initial velocity vector be pointed to...
  9. C

    Escape velocity of an artificial satellite

    Hey, I'm doing a research on artificial satellites, and I'm really confused about the escape velocity required for an artificial satellite to escape from the gravitational attraction of the Earth. I know that the equation for it is v^2 = 2GM/r , and with that, the rocket should launch at that...
  10. Greg Bernhardt

    What is Escape Velocity and How is it Calculated?

    Definition/Summary The minimum launch speed needed to ensure a projectile on the surface of a body will completely break free from its gravitational pull. Escape velocity (being a speed, rather than a velocity) is a scalar. Escape velocity is the same for any mass of projectile, and for...
  11. W

    Black Holes and escape velocity

    It is my understanding that at the most fundamental level, a black hole is simply an object with a gravitational field so strong that there exists a sphere that lies outside the body of mass of that object from which the escape velocity is equal to the speed of light. In other words, a body of...
  12. R

    How Much Air Escapes from a Heated Compressed Air Cylinder?

    Homework Statement A cylinder containing 19 kg of compressed air at a pressure 9.5 times that of the atmosphere is kept in a store at 7 degrees Celsius. When it is moved to a workshop where the temperature is 27 degrees Celsius a safety valve on the cylinder operates, releasing some of the...
  13. dean barry

    Is the Barycentric Escape Velocity Independent of the Mass of the Escaping Object?

    After calculating the gravitational PE using : PE = ( G * m1 * m2 ) / d Then i split the result into KE between the two bodies according to the ratio of the masses, then calculated the individual velocities from those (based on KE = ½ * m * v ²) Any comments ?
  14. xortdsc

    Escape velocity of electron/positron pair

    Hi, is there a way to compute the escape velocity/kinetic energy of a newly created electron/positron pair ? Or in other words: How much excess energy (beyond 2 times electron mass) has to be put into the creation such that they will escape each other into infinity ? Thanks and cheers
  15. C

    Escape velocity and tangential impulse

    Here is the problem. A rocket of mass m is in a circular orbit around the Earth at a distance R from the center. (a) What tangential impulse, mΔv, must be given to the body so that it just escapes to infinity? My attempt: I set the problem in terms of energy...
  16. D

    Escape Velocity Calculations for Multiple Masses

    Hello, I had some questions on escape velocity. The only methods that I have seen on escape velocity involve the assumption that the mass which is "being escaped from" remains at rest (at a fixed point in space). For example the method of determination of escape velocity using Ki+Ui=Kf+Uf seems...
  17. V

    Escape velocity of a satellite

    The escape velocity of a satellite circularly orbiting a large body comes from conservation of energy. Are there any modifications that must be made for the escape velocity of an elliptical orbit? Thanks in advance!
  18. K

    Conservation energy to find escape velocity

    Guy, i have a problem. When we use conservation energy to find the escape velocity, ie the root of potentiality is unlimited, why we don't compute the velocity of earth? We knew the Earth rotated its axis, then everything in surface was had linear velocity. So when we launch a thing, it's...
  19. A

    Can we escape a black hole's event horizon using another?

    I have always assumed once we pass through a black hole's event horizon, we can throw away the return ticket. But I have been thinking - is it really so final? Consider two identical black holes close to each other with their even horizons overlapping, or nearly so. Is the spacetime on a...
  20. T

    Equations for Apollo Spacecraft Orbital Velocity & Moon Escape Velocity

    Look for help on these equations. Any help will be greatly appreciated. Thanks so much! :) The Apollo spacecraft must be traveling at what velocity in order to remain in a 110 kilometer orbit around the moon? The magnitude of the Apollo’s orbital velocity can be computed from the laws of...
  21. A

    If gasses escapes Earth, then how do they reach escape velocity?

    :confused:
  22. S

    Trouble understanding the idea of escape velocity

    I'm having trouble understanding the idea of escape velocity. How can an object escape the gravity of a massive object like the Earth? No matter what the velocity the object is, doesn't Newton's law of gravity imply that eventually, the force of gravity will cause the object to decelerate, and...
  23. M

    Vapour Pressure: Exploring How Molecules Escape Into Gas Phase

    I read in my Chemistry workbook that: "At higher temperatures, vapour pressure increases as more energy is provided to the liquid molecules, allowing them to escape into the gas phase." At the boiling point, all energy is gone into breaking bonds and to convert liquid phase molecules into...
  24. Ascendant78

    Escape energy required for an orbiting body?

    My current level of knowledge is based on Physics I and my own readings, so bear with me if this is something relatively simple that I'm overlooking... Anyway, my question is regarding the energy required for an orbiting body to escape orbit? I understand the formula of escape velocity where...
  25. elDuderino81

    Finding Planetary Radius using density and escape velocity

    [b]1. "Calculate the radius of a planet with mean density of 3.0x10^3 m2kg-3, from which a golf ball can be thrown to infinity as a velocity of 40 ms-1" Homework Equations I've been looking at the equation of: Vesc=sqroot of 2*G*M/r and rearranging to r=2*G*M/Vesc. However, the...
  26. G

    Derivation of Schwarzschild radius from escape velocity

    Hi, Is it pure coincidence that if you put ##c=v_e=\sqrt{2GM/R}## in the escape velocity, you end up with the Schwarzschild radius ##R=2GM/c^2##? The derivation of the escape velocity is purely classical mechanics. It involves ##E_{kin}=mv^2/2## which is incorrect in special relativity...
  27. I

    Can information escape a blackhole?

    Hello everybody, this is my first post to the forum. I am trying to learn concepts in physics at the moment. According to the theory, the concentrated mass of a black hole warps space-time so much, that not even light can escape the event horizon. I have a thought experiment. Say, half the...
  28. R

    If enough heat is applied to an object, will it reach escape speed?

    This is just something I'm wondering, if we apply enough heat to an object, and since the speed of the molecules inside it is directly measured by temperature, will the molecules inside the object move fast enough to reach the escape speed of the planet that it is on? I know that this is the...
  29. R

    How to find the escape speed of moon Titan?

    Homework Statement Saturn’s moon Titan is the only moon in the solar system with an atmosphere, which is 95% nitrogen molecules (N2), similar to Earth’s atmosphere. At Saturn’s distance from the Sun, the temperature of the atmosphere is only 95 K (−180◦ C), and the molecules have an average...
  30. A

    Escape Velocity from Earth-Moon System

    Homework Statement A projectile is fired straight away from the moon from a base on the far side of the moon, away from the earth. What is the projectile's escape speed from the earth-moon system? m_earth= 5.97x10^24kg m_moon= 7.348x10^22kg radius_earth= 6.371x10^6mHomework Equations...
  31. K

    Why Does the Escape Velocity Decrease as Mass Increases in an Electric Field?

    Upon applying the method of finding escape velocity to the E-field, I end up with: \sqrt{\frac{2kQq}{rm}} What I don't understand, conceptually, is why escape velocity decreases as mass increases, in the electric field. What property is actually taking place here?
  32. M

    Need help with escape velocity practice problem

    Homework Statement The radius of Saturn (from the center to just above the atmosphere) is 60300 km (60300✕103 m), and its mass is 570✕1024 kg. An object is launched straight up from just above the atmosphere of Saturn. What initial speed is needed so that when the object is far from...
  33. G

    What is the time taken to reach a given height with escape velocity?

    If an object is launched at escape velocity from the surface of the Earth, how long will it take to reach a given height h? Ignoring air resistance and other gravity, etc.
  34. H

    What Determines the Escape Speed from Earth's Gravitational Pull?

    Hi friends. Somewhere in a reference book I read about escape speed of a particle for earth. Let a particle is projected from the Earth surface. Let its mass be m and speed of projection be u. Let mass of Earth be M and its radius be R. According to law of conservation of energy...
  35. T

    Leap Off an Asteroid: Escape Earthly Gravity?

    Suppose that on Earth you can jump straight up a distance of 50 cm. Can you escape from a 4.0-km-diameter asteroid with a mass of 1.0 times 10^14 kg?
  36. S

    More on gravitational time dilation and escape velocity.

    First, thanks for all the replies to the first post. I was able to predict this result (an engineer did the proof) using an analogy for gravitation I worked out to replace the standard marble rolling on a rubber sheet analogy used to show the effect of curved space time, which is useless on a...
  37. S

    Gravitational time dilation and escape velocity

    The time dilation caused by gravity on the surface of a planet is equal to the time dilation for an object moving at the planet's escape velocity in space. This can be proved using the Schwarzschild metric. GR doesn't explain why this is true. It seems to be an odd coincidence.
  38. Q

    Calculating Escape Velocity of Mars from the Sun's gravitational field

    1) The problem: Mars orbits the Sun at a distance of 2.3 * 10^10 m with a speed of 24000 m/s. If it's speed were increased to 30000 m/s, at a time when no other planet was nearby, would Mars leave the Solar System. 2) Fc=Fg Orbit formulas and such 3) I'm assuming you have to find the escape...
  39. T

    Escape velocity for object on Earth

    Homework Statement Suppose the gravitational force of the Earth on a body was F = \frac{KMm}{r^3}. What escape velocity would a body need to escape the gravitational field of the Earth? Homework Equations v_e = \sqrt{\frac{2GM}{R}} F_g = G*\frac{m_1*m_2}{r^2} The Attempt at a...
  40. MarkFL

    MHB Using Snell's Law to determine the fastest escape route

    On another forum the following question was asked: This was my initial reply: Let: $L$ = distance upstream to the safehouse $W$ = width of the river $v_s$ = swimming speed $v_r$ = running speed All variables above are assumed to be positive. I have set it up as follows...
  41. AnTiFreeze3

    A Peaceful Escape: Finding the Ideal PF Island

    Society blows. I'm sure that most people have contemplated getting away from it all and just living a peaceful life in solitude. However, humans are social creatures, and there are benefits to having other people around. As a solution, I propose that there be a society of like-minded...
  42. B

    Does the angle at which an object is fired affect its escape velocity?

    The escape velocity of an object on the surface of the Earth is the minimum speed required for it to "break free" from the Earth's gravitational field without requiring further propulsion. Its value is mathematically determined to be v = \sqrt{\frac{2GM}{R}} with M being the mass of the Earth...
  43. B

    Escape Speed of a Satellite

    A satellite of mass 7500 kg orbits the Earth in a circular orbit of radius of 7.3(10^6) m (this is above the Earth's atmosphere). The mass of the Earth is 6.0(10^24) kg. What is the minimum amount of energy required to move the satellite from this orbit to a location very far away from the...
  44. J

    What's the point of Escape Velocity?

    Hi everyone and thanks for this great forum! I don't understand how is calculating escape velocity important to space travel. I think I am right to say that you can never really escape the gravity of a body. However far your rocket goes, be it 400km or 14 billion light years and making the...
  45. E

    Escape Velocity for Moon: Is the Equation Wrong?

    v,escape = (2*mu/r)^(1/2), where mu = G*M. What I'm asking is if this page is wrong about calculating the escape velocity for the moon. They seem to have the equation wrong (missing 2 in front of mu = G*M,moon).
  46. Q

    Schwarzchild radius and escape velocity?

    We know that the escape velocity at the schwarzchild radius is c. Since the escape velocity is defined as the velocity needed to escape from the gravitational field, to reach a total energy of 0 at infinity: Doesn't this mean that an object falling from infinity starting at rest, to the...
  47. A

    Escape Velocity Calculation for a Spaceship in Space

    Homework Statement What is the escape speed of a spaceship fired in space, far away from Earth but at the same distance from the sun as the Earth. Homework Equations Ve = (2GM/r)^0.5 The Attempt at a Solution The problem is that I don't know what the M or r is since it is fired...
  48. W

    How Do You Determine if a Meteoroid Has an Open Orbit?

    Homework Statement A meteoroid with a velocity (when the effect of the Earth's gravity has been eliminiated) of 49.9 km/s when it is at a distance of 1.50x10^11m from the sun. (a) Using energy calculations show that this object has an open orbit and is therefore not restricted to our solar...
  49. O

    Escape velocity of solar system

    Hey guys so this question I'm kind of stuck on, Our solar system, starting from Saturn's orbit. So I know the formula is v = sqrt(2GM/r) But not sure what to put for the mass and radius, am i including saturn and planets like uranus and neptune only or all the satellites and stuff to like...
  50. B

    Thermodynamics involving escape velocity and Boltzmann factor

    At 293K, helium atoms have a root mean square speed of about 1.35 km/s, whereas escape velocity at the Earth's surface is about 11km/s. Explain why is it nevertheless possible for helium atoms to escape from the Earth into space. Is it because near the top of the atmosphere the temperature...
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