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Thread: i need a question answered pretty ergently

  1. #1 i need a question answered pretty ergently 
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    i have question on my mind just a curiosity and that is that can something be moved just by hitting it with light?

    for example if i shined an extremely powerful light at a tiny slither of paper would it move at all.(if there was no friction or resistance?)

    it has just been something i am curious about.

    i think my dad was telling me how in his science class they hung a massive lead ball and started throwing scrunched up pieces of paper at the lead ball.


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  3. #2  
    Administrator KALSTER's Avatar
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    Yes, it does impart some momentum on a surface, but only a small amount. I am trying to look for some material on this....


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  4. #3  
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    The momentum of a photon equals h/lambda, where h is Planck’s constant and lambda is the wavelength of the light in vacuum.
    http://www.aip.org/pnu/2005/split/732-1.html
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  5. #4  
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    thanks that realy helps at least i think it is im almost cirtain it makes sence in a very right way.
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  6. #5  
    Moderator Moderator John Galt's Avatar
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    The concept has been exploited in designs for light sails - gigantic sheets of very thin material - attached to a payload, that could navigate through the solar system.
    http://en.wikipedia.org/wiki/Light_sail
    http://www.tsinghua.edu.cn/docsn/lxx...es/Page567.htm
    http://www.sff.net/people/Geoffrey.L...ghtsail89.html
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  7. #6  
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    i thought some1 might make a solar sailing ship (dammm) i was thinking about that you know that movie treasure planet.(look at the ships in the movie.disney movie) they have solar sails except theres also get power from the sails)
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