# Differing velocities in zero gravity?

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#### Marikurisato

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<p>I feel horrible for making my first post a question-begging thread, but I can't seem to word the question in a fashion that returns a relevant answer from search queries, so...<img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-embarassed.gif" border="0" alt="Embarassed" title="Embarassed" /></p><p>&nbsp;</p><p><font color="#0000ff">if a&nbsp; vehicle&nbsp; travelling at say 16,000 km/s in a straight line in space/zero g with no nearby planetary objects releases a smaller object from&nbsp; itself, what happens to the smaller object? Does it match speed given the original vessel's velocity and lack of atmosphere to cause drag? Does it lose velocity due to having no propulsion of it's own?</font></p><p>&nbsp;</p><p>Again, sorry if this post is in any way irritating or posted in ignorance of existed protocols, but this question has been bugging me for a month now. Thanks for reading!</p> <div class="Discussion_UserSignature"> <p>__________________- </p><p>"why?"</p> </div>

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#### Marikurisato

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Sounds like a homework question.&nbsp; To be precise I'd want to know what's meant by the word "releases".&nbsp; For the moment let me assume the scenario is like a space shuttle coasting faaaaar out in space so there's neglible gravity from any planet or star or anything.&nbsp; The shuttle holds a small ball at the end of it's arm at some distance away. It then let's go without any pushing or pulling on the ball.&nbsp; So the thing to remember is that in this case good old Newtonian mechanics will give you a good answer; in particular F=MA or, re-arranging, A=F/M.&nbsp; So what forces are acting on the shuttle ?&nbsp; What forces are acting on the ball after it's release ?&nbsp; In general if there's no acceleration, what happens to velocity ? ...to position ??FWIW there's the simple approximation and then there's a better one.&nbsp; For the better, truer answer remember Newton's Universal law of Gravitation; ie -&nbsp;gravity is a force (F) arising from what ?If your question was a homework assignment I apologise for being obtuse but I think you can figure it out from here. If not, post back.&nbsp; <br /> Posted by mee_n_mac</DIV></p><p>&nbsp;I haven't been in college for ten years, actually, but I love the idea of the challenge. Having failed even remedial math I'll need to go study those equations, but I appreciate the hints! Thanks so much! </p><p>&nbsp;____</p><p>&nbsp;Ok, with some awesome hints from mee_n_mac&nbsp; I think the law that applies is "An object that is in motion will not change its velocity (accelerate) until a net force acts upon it." The article goes on to discuss that even in outer space there is friction or some net force acting upon it, which in this hypothesis let's assume is the pull of a star 18 billion kilometers away. Would the force of such a star have a noticeably effect though?</p><p>fun fun ponderings! </p><p>&nbsp;</p> <div class="Discussion_UserSignature"> <p>__________________- </p><p>"why?"</p> </div>

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#### Marikurisato

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'> &nbsp;.No doubt some more informed than I can give you a better rundown of all the forces involved in spaceflight.&nbsp; <br /> Posted by mee_n_mac</DIV></p><p>not, it gives me a lot to ponder as it, and you are &nbsp;very awesome for that! Would that I could send you cookies through the internet ( no, not those kind) that was very helpful! Thanks!</p> <div class="Discussion_UserSignature"> <p>__________________- </p><p>"why?"</p> </div>

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