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Thread: Escape Velocity.. :S

  1. #1 Escape Velocity.. :S 
    Forum Freshman Captain_Anubis's Avatar
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    I don't understand the concept of escape velocity. It's supposed to be the minimum speed at which you must move in order to escape some mass with a gravitational force. The way i see it is shouldn't it be more of an escape acceleration?? If you could get an engine that pushed some 1kg mass with 10N up for a second and then reduced to exactly G and stayed at whatever G is at any distance from Earth wouldn't that get you off of the planet with a velocity of next to nothing?? Or an I misunderstanding the concept.. :S


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  3. #2 Re: Escape Velocity.. :S 
    Forum Senior Imaplanck.'s Avatar
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    Quote Originally Posted by Captain_Anubis
    I don't understand the concept of escape velocity. It's supposed to be the minimum speed at which you must move in order to escape some mass with a gravitational force. The way i see it is shouldn't it be more of an escape acceleration?? If you could get an engine that pushed some 1kg mass with 10N up for a second and then reduced to exactly G and stayed at whatever G is at any distance from Earth wouldn't that get you off of the planet with a velocity of next to nothing?? Or an I misunderstanding the concept.. :S
    It definately is escape volocity not acceleration. Its the velocity needed for your mass(m2) to travel so that the gravity of m1 curves the path of your mass less than the curvature of the surface of m1.


    "A man's ethical behavior should be based effectually on sympathy, education, and social ties; no religious basis is necessary. Man would indeeded be in a poor way if he had to be restrained by fear of punishment and hope of reward after death." Albert Einstein
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  4. #3  
    Forum Isotope Zelos's Avatar
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    if a object with mass m have 0 in PE and V=0 at infinite distance from another object with amss M it have will have the potensial energy -GMm/R at distance R
    using some classic stuff that EK = mV²/2
    and because energy cant come from nowhere, exept in QM, EK+PE must allways be the same aslongest nothing else takes it.
    with our writing its mV²/2-GMm/R = 0 because it didnt have any KE or PE in the begining
    some rearangement we get
    mV²/2=GMm/R
    little more rearangement
    V=sqr(2GM/R)
    this have all to do with the law of energy conservation not acceleratoin. u can also see that the mass of the object leaving doesnt effect it.
    but if u know the mass of the oibject m u can calculate the thrust needed by using impulse law
    I=FT=dP=m*dv=m*V
    then divide it with the time wich it takes and u´ll get the minimum amount of netforce required to get it into outer space. but notice its the netforce, to get the total amount of force u´ll have to take F+mg
    I am zelos. Destroyer of planets, exterminator of life, conquerer of worlds. I have come to rule this uiniverse. And there is nothing u pathetic biengs can do to stop me

    On the eighth day Zelos said: 'Let there be darkness,' and the light was never again seen.

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  5. #4 Re: Escape Velocity.. :S 
    Forum Freshman Captain_Anubis's Avatar
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    Quote Originally Posted by Imaplanck.
    Quote Originally Posted by Captain_Anubis
    I don't understand the concept of escape velocity. It's supposed to be the minimum speed at which you must move in order to escape some mass with a gravitational force. The way i see it is shouldn't it be more of an escape acceleration?? If you could get an engine that pushed some 1kg mass with 10N up for a second and then reduced to exactly G and stayed at whatever G is at any distance from Earth wouldn't that get you off of the planet with a velocity of next to nothing?? Or an I misunderstanding the concept.. :S
    It definately is escape volocity not acceleration. Its the velocity needed for your mass(m2) to travel so that the gravity of m1 curves the path of your mass less than the curvature of the surface of m1.
    Ok, so it's how fast you have to be moving along the surface of Earth to force yourself into orbit... cool ^^
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  6. #5 Re: Escape Velocity.. :S 
    Forum Senior Imaplanck.'s Avatar
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    Quote Originally Posted by Captain_Anubis
    Quote Originally Posted by Imaplanck.
    Quote Originally Posted by Captain_Anubis
    I don't understand the concept of escape velocity. It's supposed to be the minimum speed at which you must move in order to escape some mass with a gravitational force. The way i see it is shouldn't it be more of an escape acceleration?? If you could get an engine that pushed some 1kg mass with 10N up for a second and then reduced to exactly G and stayed at whatever G is at any distance from Earth wouldn't that get you off of the planet with a velocity of next to nothing?? Or an I misunderstanding the concept.. :S
    It definately is escape volocity not acceleration. Its the velocity needed for your mass(m2) to travel so that the gravity of m1 curves the path of your mass less than the curvature of the surface of m1.
    Ok, so it's how fast you have to be moving along the surface of Earth to force yourself into orbit... cool ^^
    Yes its like you are always moving in a straight line but when you are under the gravitational influence of another mass(the earth for instance) the space around that mass is distorted so your path is essentially curved, the amount of curve is dependent on your velocity not acceleration.
    "A man's ethical behavior should be based effectually on sympathy, education, and social ties; no religious basis is necessary. Man would indeeded be in a poor way if he had to be restrained by fear of punishment and hope of reward after death." Albert Einstein
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  7. #6 Re: Escape Velocity.. :S 
    Forum Isotope Zelos's Avatar
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    Quote Originally Posted by Captain_Anubis
    Quote Originally Posted by Imaplanck.
    Quote Originally Posted by Captain_Anubis
    I don't understand the concept of escape velocity. It's supposed to be the minimum speed at which you must move in order to escape some mass with a gravitational force. The way i see it is shouldn't it be more of an escape acceleration?? If you could get an engine that pushed some 1kg mass with 10N up for a second and then reduced to exactly G and stayed at whatever G is at any distance from Earth wouldn't that get you off of the planet with a velocity of next to nothing?? Or an I misunderstanding the concept.. :S
    It definately is escape volocity not acceleration. Its the velocity needed for your mass(m2) to travel so that the gravity of m1 curves the path of your mass less than the curvature of the surface of m1.
    Ok, so it's how fast you have to be moving along the surface of Earth to force yourself into orbit... cool ^^
    that is just stupid. no its the speed u need straight up. 90° from the land. and this is not the speed for ORBIT. its the speed equired to LEAVE earth enterily. with orbit u need it to be less. if u want i can write that formula aswell
    I am zelos. Destroyer of planets, exterminator of life, conquerer of worlds. I have come to rule this uiniverse. And there is nothing u pathetic biengs can do to stop me

    On the eighth day Zelos said: 'Let there be darkness,' and the light was never again seen.

    The king of posting
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  8. #7 Re: Escape Velocity.. :S 
    Forum Senior Imaplanck.'s Avatar
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    Quote Originally Posted by Zelos
    Quote Originally Posted by Captain_Anubis
    Quote Originally Posted by Imaplanck.
    Quote Originally Posted by Captain_Anubis
    I don't understand the concept of escape velocity. It's supposed to be the minimum speed at which you must move in order to escape some mass with a gravitational force. The way i see it is shouldn't it be more of an escape acceleration?? If you could get an engine that pushed some 1kg mass with 10N up for a second and then reduced to exactly G and stayed at whatever G is at any distance from Earth wouldn't that get you off of the planet with a velocity of next to nothing?? Or an I misunderstanding the concept.. :S
    It definately is escape volocity not acceleration. Its the velocity needed for your mass(m2) to travel so that the gravity of m1 curves the path of your mass less than the curvature of the surface of m1.
    Ok, so it's how fast you have to be moving along the surface of Earth to force yourself into orbit... cool ^^
    that is just stupid. no its the speed u need straight up. 90° from the land.
    No its not completely stupid! If you imagine the earth as a completely smooth sphere with no atmosphere and you speed along the surface at the escape velocity and you maintain that velocity indefinately you will eventually escape. Its not dependant on being perpendicular to earth, if you are in orbit and accelerate to escape velocity you will escape, Parallel, perpendicular or anywhere in between - THE ESCAPE VELOCITY IS THE SAME. C anubis made a valid analogy.
    "A man's ethical behavior should be based effectually on sympathy, education, and social ties; no religious basis is necessary. Man would indeeded be in a poor way if he had to be restrained by fear of punishment and hope of reward after death." Albert Einstein
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  9. #8  
    Forum Isotope Zelos's Avatar
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    im ready to bet my ass that it doesnt matter what planet u leave from with a significan earthlike size would result in disaster if u did it with 00°, of course 90° but when i think on it, ure right, my bad
    I am zelos. Destroyer of planets, exterminator of life, conquerer of worlds. I have come to rule this uiniverse. And there is nothing u pathetic biengs can do to stop me

    On the eighth day Zelos said: 'Let there be darkness,' and the light was never again seen.

    The king of posting
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