Escape Definition and 374 Threads

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. K

    Horizontal escape of a projectile

    Homework Statement The problem is attached Homework Equations L=mr^2(dr/dt) V_escape=(GM/R)^.5 E=L^2/(2mR^2)-(GMm)/R=0 The Attempt at a Solution after some work i got: dr/dtheta=((r^3/R)-r^2)^1/2 dont know what to do from here. Thanks.
  2. N

    Can the escape velocity be achieved at any angle?

    So I looked at a neat derivation for what the minimun escape velocity is, and It was pretty clever. Because this is conserved: KE + PE = 1/2 *mv^2 + -GMm/r You can find what the velocity would have to be to get to infinity with zero velocity 1/2 *mvesc^2 + -GMm/r = 1/2 *m(0)^2 +...
  3. H

    Why escape velocity is independent of angle of projection

    can someone explain physically why escape velocity is independent of angle of projection.
  4. B

    Help Applications of Differential Equations to Escape velocity

    Okay, in the Escape Velocity Equation, with the usual notations, v2=2gR2/r + (v02-2gR) a few articles like [PLAIN]"www.math.binghamton.edu/erik/teaching/02-separable.pdf"[/URL]give the following explanation: ... ... ...(implying that v0>=√2gR) That raises a few doubts in my mind...
  5. T

    Deriving the Relation for Escape Velocity from a Proto-Star Cloud

    : Derive a relation for the escape velocity of an object, launched from the center of a proto-star cloud. The cloud has uniform density with the mass of M and radius R... Ignore collisions between the particles of the cloud and the launched object. If the object were allowed to fall...
  6. B

    What is the Difference Between Escape Velocity and Orbit Velocity?

    "Given a planet has mass M and radius R, find the speed it would have to be launched at. Compare this to the speed required to put the object in the circular orbit." I understand the first half where Ep=Ek i.e: GMm/r = 1/2 mv2 rearrange to find v how ever, I'm unsure of what exactly...
  7. M

    How does the jetstream of particles manage to escape from the blackhole?

    There is a jetstream of particles (mostly electrons and photons) coming out of the black hole. But nothing escapes from a black hole because its gravity is so strong. So how do these particles come flying out of a black hole?
  8. M

    What is the Escape Velocity of a Satellite in Orbit?

    Homework Statement A satellite is in orbit around a planet with orbital speed determined to be 7080 m/s. Find the escape velocity from the planet from this position of its orbit. Homework Equations EV=sqrt(2GM/r) The Attempt at a Solution With a problem like this, I would just...
  9. C

    Escape Velocity Altered by Other Masses?

    Earth's Escape velocity is approximately 11.2 km/s, which is derived from the equation v = (2GM/R)^1/2. I know that this equation is derived from energy conservation, K + U = 1/2mv^2 + (-GMm/r). My question is regarding the addition of other masses to this equation based on location...
  10. R

    How can hawking radiation escape?

    how can hawking radiation escape from a black hole? thanks
  11. D

    Is there a certain material that absorbs X-Rays so that the X-Rays don't escape

    Is there a certain material that absorbs X-Rays so that the X-Rays don't escape. Or rather, is there a material that stops the X-Rays from continuing. If there is such a material, is there a way to change the X-Ray into an electrical current?
  12. C

    Escape from a black hole with another black hole?

    Greetings, The event horizon of a black hole is supposedly a point of no return. But can't the presence of another gravitational source decrease the event horizon? If you are between two sources of gravity isn't it easier to move away from either one? If immediately after a particle crosses...
  13. V

    Why can't light escape black holes?

    Hello, I am aware that this question was the subject of a topic on this site, but it did not fully answer my question. My question is, why can't light escape from a black hole's gravitational pull, when, according to general relativity, the speed of gravity is equal to the speed of light? My...
  14. A

    Can someone calc these escape velocities?

    maybe this will make it easy for you to understand. when in Earth at a radius of 9.27e4, you tell me what the escape velocity is? when in the moon at a radius of 2.14e4, you tell me what the escape velocity is? when in the sun at a radius of 6.43e6, you tell me what the escape velocity...
  15. A

    Can anyone help mess around with escape velocities?

    v=(gr2)^.5 i assume that g is directly related to r as g = Gm/r^2 in such I started to wonder when, if ever, will v = r as an INTEGER ONLY NOT DIMENSIONS? v = ( 2 * g * r )^.5 v = ( 2 * G * ( m / r^2 ) * r )^.5 v = ( 2 * G * m / r )^.5 v * r^.5 = ( 2 * G * m )^.5 REMEMBER! v=r at some point...
  16. M

    Exploring Escape Velocity and Forces

    Hi guys! I want to ask something about escape velocity. I know the definition of EV "escape velocity is the speed at which the kinetic energy plus the gravitational potential energy of an object is zero"(wikipedia). Can we approach the problem by equalling the attractive force to the...
  17. P

    Spaceship Escape speed understanding

    Homework Statement A spaceship is launched from the Earth's surface with a speed v. The radius of the Earth is R. What will its speed be when it is very far from the Earth? (Use any variable or symbol stated above along with the following as necessary: G for the gravitational constant, m for...
  18. A

    Fraction of stimulated photons that escape from a laser cavity

    How to calculate the fraction of stimulated photons that escape from a laser cavity with alpha=0.1 cm^-1 length of cavity=1mm refractive index of laser cavity=3.2 the photons are assumed to be escaping into air so approx refractive index is 1. Im assuming that alpha is some sort of...
  19. M

    How High Can a Rocket Go Using Liquid Oxygen and Kerosene?

    Homework Statement A 20000kg spacecraft carrying 17000kg of fuel starts at the surface pf the earth, (Mass=6*1024kg, radius of 6.3*10^6 m). The liquid oxygen and kerosene rocket provides an exhaust velocity of 3500m/s. a.) How much high can the rocket go above the Earth's surface? b.)Once...
  20. A

    Calculating Energy for Orbital Deployment

    Homework Statement A scientist wants to put an 100kg experimental package in orbit around the Earth. The cost of deployment depends on the amount of extra energy it takes to get it into the required position i.e. how much more energy is used than just sending the rocket up there. a)...
  21. P

    Calculating radius based on escape velocity and density? PLEASE HELP

    Homework Statement A spherical asteroid has a density of 2600 kg/m^3. I throw a ball at the speed on 20 m/s. If the ball is to travel in a circular orbit, what is the largest radius of the asteroid possible to accomplish this? Homework Equations these are the equations I used.. escape...
  22. G

    What is the Maximum Height Attained by an Object Launched from Earth's Surface?

    Homework Statement An Object is fired vertically upward from the surface of the Earth ( of radius RE ) with an initial speed vi that is comparable to but less than the escape speed vesc Show that the object attains a maximum height h given by h=\stackrel{R_{E}v^{2}_{i}}{v^{2}_{esc}-v^{2}_{i}}...
  23. 7

    What is the maximum tension in the makeshift rope for a jail escape attempt?

    A 75 kg petty third wants to escape from a third story jail window. Unfortunately, a makeshift rope of sheets tied together can support a mass of only 50 kg. What is the minimal acceleration with which the thief must lower himself so he may use the "rope" without breaking it? the variables i...
  24. nukeman

    Moon Question (Vacuum, air, escape vel.)

    Ok, this might seem like a silly question, but I just want to get it straight. Just tell me if anything I am saying is wrong, and answer the best you can. Ok, the moon has no air, because it has no atmosphere correct? And the reason for no atmosphere is because the moon is biologically...
  25. L

    Estimate the radius of the largest asteroid you could escape by jumping

    Homework Statement estimate the radius of the largest asteroid from which you could escape simply by jumping off. Homework Equations R^2= 3gh/4piGp The Attempt at a Solution Would I use this formula to solve it? Found it online but dose not seem right. this is a 2 part problem...
  26. G

    What is the relationship between escape velocity and orbital velocity?

    I am trying to understand the existence of orbits apart from the elliptical one. I have used the following line of thought. Consider an object moving from infinity towards a planet. The object has kinetic energy alone at infinity. But it develops a potential energy as it comes closer to the...
  27. U

    Escape velocity when in earth's orbit

    I have a problem where it ask to find the period/time(using Kepler's 3rd law) of an unpowered spacecraft to move from Earth's orbit to Mars orbit using the transfer orbit approach. I found P/T using kepler's 3rd law but the second part ask to find how fast the spacecraft need to be moving at...
  28. M

    1 dimensional motion escape from a locked door

    Homework Statement [PLAIN]http://img443.imageshack.us/img443/3598/physicsproblem.png Homework Equations Ok so I am first of I don't know when they said layer if they meant the number of people or the thickness? of the people I don't understand the question The Attempt at a Solution what I...
  29. R

    Why Is Calculating Escape Velocity Different from Determining Orbital Speed?

    I tried finding the equation for terminal velocity in a broader attempt to understand planetary orbits better. According to wikipedia's two derivations (one of which i don't understand very well) I'm off by a factor of \sqrt 2 . I would greatly appreciate help in finding my thinking/math...
  30. L

    Mangetic and electric field, optics and escape velocity questions

    http://img682.imageshack.us/i/77482562.jpg/" I don't really understand these questions... Is there anyone who could tell me HOW to solve them? I don't ask about ONLY answers, I just want to understand how to solve these types of exercises. The things I know: 1. the centrifugal force =...
  31. B

    Orbital transfers and escape velocity: relationship

    I have been told that there is no interaction between the gravitational fields of the sun and any planet, but the issue continues to stimulate my curiosity. If the Earth orbits the sun at 30km/s, how could anything achieve an orbital speed around Earth at greater than 30km/s without...
  32. I

    Greatest elongation and escape velocity HELP

    Homework Statement Three wires are made of same materials. Which wire will have the greatest elongation? wire1: length: 50cm, diameter: 0.5mm wire2: length: 100cm, diameter: 1mm wire3: length: 300cm, diameter: 3mm Homework Equations The Attempt at a Solution I know, the wire having greatest...
  33. S

    Electricffiledcalcuate escape speed

    electricffiled..calcuate escape speed! urgent please help Homework Statement Homework Equations ke=1/2mv^2 Ue=Eqs E=kq/r^2 The Attempt at a Solution Uf+kf=Ki+Ui Uf=0 and Kf=0 so -Ui=Ki Eqs=1/2(mv^2) v=(sEqs/m)^1/2 after this no clue i got lost help please
  34. D

    Is there a formula in electrostatics analogous to escape velocity?

    I was trying to understand the similarities and differences between electrostatics and standard Newtonian mechanics, in particular gravitational formulas. One thing I was curious about is escape velocity. For gravity I've learned that it's sqrt(2GM/R). But for electrostatics, suppose I was...
  35. D

    Centripetal force or escape velocity?

    Homework Statement A certain spherical planet which is not rotating has a radius of 6.36 x 105 m and a mass of 1.89 x 1021 kg. At what minimum speed would a vehicle traveling along its surface just begin to leave the ground? Homework Equations FC = mv2/r FG = GMm/d The Attempt at a...
  36. Philosophaie

    Sagitarius A and its Possible Escape from a Black Hole

    Sagitarius A or SgrA is a star rotating near the center of our Milky Way Galaxy. Located at Ecliptic Longitude of 27sgr00 right now. The velocity of SgrA must be tremendous. What is the prognosis that it will collide with the black hole? This supermassive Black Hole will soon engulf...
  37. C

    Relating escape velocity equations

    Homework Statement I'm having a hard time relating the escape velocity equations, sqrt(2GM/r) to sqrt(2gr) The Attempt at a Solution I know that both equations mean the same thing, but I can't figure out how to get from the first equation to the second
  38. C

    Can a Magnetic Field Escape a Black Hole?

    If light can't escape a black , Then can a magnetic field escape a black hole , If the B field has an energy density , and if it has energy associated with it then it should be affected by gravity .
  39. P

    Projectile Escape Trajectory: Solving for Earth's Radius at Maximum Height

    Homework Statement A projectile is shot directly away from Earth's surface. Neglect the rotation of the Earth. What multiple of Earth's radius RE gives the radial distance (from the Earth's center) the projectile reaches if (a) its initial speed is 0.225 of the escape speed from Earth and (b)...
  40. P

    Comparing Escape Energies of Earth, Moon, and Jupiter

    Homework Statement What multiple of the energy needed to escape from Earth gives the energy needed to escape from (a) the Moon and (b) Jupiter? Use the Table (link below) if necessary http://edugen.wiley.com/edugen/courses/crs1650/art/qb/qu/c13/fig13-19.gif Homework Equations...
  41. S

    Why does air escape through a pinched ballon?

    Hello guys, This is simple question but I have gone completely blank. Ok let's say there was a balloon outside that was inflated. This means that it has expandes so it's pressure is equivalent to atmpospheric pressure right? So when I pinch it why does air escape, how does balloon suddenly...
  42. T

    Escape Velocity (from surface of the Earth)

    Homework Statement A satellite with a mass of 5.00x10^2 kg is in a circular orbit, whose radius is 2re, around Earth. Then it is moved to a circular orbit with a radius of 3re. e) Calculate the escape velocity for the satellite if it is on Earths surface. Homework Equations Vesc =...
  43. A

    Escape velocity of solar system projectile

    Homework Statement A projectile is fired from the Earth in the direction of the earth’s motion around the sun. what minimum speed must the projectile have relative to the Earth to escape the SOLAR SYSTEM? Ignore the earth’s rotation. Homework Equations escape velocity = sqt[(2G x...
  44. K

    What is the Escape Speed of an Electron from a Charged Glass Sphere?

    \sqrt{}Homework Statement What is the escape speed (in m/s) of an electron launched from the surface of a 7.42 cm diameter glass sphere that has been charged to 7.04 nC? Homework Equations u=kqq/r KE=1/2MV^2 UO=KE The Attempt at a Solution here is what i did kqq/r = 1/2mv^2...
  45. Y

    Escape velocity of a spoked wheel.

    Consider a spoked wheel of radius r. The instantaneous tangential velocity of a point on the rim is v. A test particle in the form of a small bead that can freely slide along a spoke when released, is placed as close to the axis as possible so that for the sake of argument its radial...
  46. J

    Discover the Mass of a Planet with an Escape Velocity of 3.60×104 m/s

    A certain planet with a radius of 8.30×107 m has an escape velocity of 3.60×104 m/s. What is the mass of this planet? How do i solve this?
  47. R

    Will the Moon escape Earth's orbit in billions of years?

    I've heard that the moon is very slowly moving away from Earth. Will it eventually escape Earth's orbit?
  48. Z

    Quick question about Escape velocity

    Okay this equation is giving me some trouble, I just have a question vescape = √(2GM)/R Say I wanted to find the escape velocity of myself 3 meters away So I would use vescape = √(2)(6.674*10^-11)((145*4.44)/9.8)/(3) = 5.419003598 *10^-5 So does this mean something that moves that slow cannot...
  49. Z

    Just a quick question of the escape velocity equation

    Okay, I just found this new equation (new to me) for the escape velocity of a body. escape velocity = √(2GM)/R So say for instance I plug this into the escape velocity of the earth I am going to say the radius is 4001 miles so I it would take a mile above the Earth to escape (4001 * 1600) =...
  50. R

    Dark energy can escape black holes.

    http://curious.astro.cornell.edu/question.php?number=760 Yep, it's an exception to the rule that "nothing can escape a black hole".
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