I have a conceptual question, suppose we have a floating object (like a satellite), inside it we generate a beam of electrons that impact a positively charged metal plate, which produces an attractive force, this internal force will move the floating object? I was convinced that it was, but they told me that the net force on the closed satellite-electron system is zero (principle of action and reaction) Since the electron beam moves independently of the satellite and the positively charged plate (where the force is produced) is linked to the satellite, so I think this attractive force will move the satellite, am I correct?
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1$\begingroup$ Think about how the rocket which put the satellite there in the first place works. :) $\endgroup$– user87745Commented May 27, 2020 at 0:58
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$\begingroup$ Possible duplicates: physics.stackexchange.com/q/439419/20427, physics.stackexchange.com/q/261155/20427. $\endgroup$– user87745Commented May 27, 2020 at 1:00
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$\begingroup$ when you say "move", do you mean "move" as in "propel"? $\endgroup$– JEBCommented May 27, 2020 at 1:01
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$\begingroup$ Well, I plan to use that force to produce a torque on the satellite. $\endgroup$– STM32Commented May 27, 2020 at 1:03
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$\begingroup$ It almost sounds like you're asking if a CRT (and associated electronics) can propel (or is it rotate? Not clear from your question) itself in space. $\endgroup$– Alfred CentauriCommented May 27, 2020 at 1:15
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The net force on the electrons+satellite system is indeed zero. But is the net force on the satellite alone (excluding electrons) zero? Since the electrons will be exerting a force on the satellite (by attracting the positive plate attached to it), the satellite does experience a non-zero net force, and hence, it does move.
