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Strength of magnetic field to attract Iron blocks

  1. Nov 26, 2011 #1
    Hi everyone. I have a simple doubt related to magnetism and inspired by the Bollywood movie 'ROBOT' starring Rajnikant.

    In the spectacular chase scene where Chitti(the robot) is trapped on a bridge with Aishwarya Rai( the heroine of the movie) and are surrounded by multitudes of policemen, he then turns on some sort of electromagnet and attracts all the guns towards him. The guns are pulled out of the hands of the police men and come flying and stick to his body. How he fires them is a different story but my question is what must be the strength of magnetic field to attract say about 40 machine guns weighing ~10kg each (400kg total) at a distance of ~25 meters or so (the distance is approximate)?
    Some considerations: 1) Magnetic field decreases exponentially from a source, so 'Chitti's' magnetic field must be quite high. 2) Since Chitti doesnt use his magnetic field always. it means it runs on an electromagnet. So once the magnetic field strength is calculated to yank out 400kg of iron from a distance of 25 meters, next question would be what is the current required to get that sort of magnetic field?

    This is just a curious question that popped in my mind. Thanks for seeing.
    The movie scene is here ( http://www.youtube.com/watch?feature=player_detailpage&v=yysbbPStfWw#t=84s )

  2. jcsd
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