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  • Re: derivation of Newton's 3rd law from 2nd law

    From Orazio Vakulovsky@21:1/5 to Tom Roberts on Fri Jul 4 21:54:47 2025
    XPost: sci.physics.relativity

    Tom Roberts wrote:

    Sure it is specified: "an external force F_ext pushing right on A". It
    really doesn't matter when on A the F_ext is applied, but the phrasing ("pushing") implies it is applied to the left side of A (remember all
    three objects are rigid). And again there is no need to assume 100N --
    any value of F_ext will do. But of course the combination of the masses
    and the force determine the acceleration a (his eq. 1).

    that's of course and error, since the world we inhabit is fluid, not
    rigid. In relativity this thing is obvious, but you have to undrestand.

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  • From Landon Mahankov@21:1/5 to Tom Roberts on Tue Jul 22 18:58:17 2025
    XPost: sci.physics.relativity

    Tom Roberts wrote:

    Your formula (1) a=100/30=3.33 m/s^2 is valid in both cases.

    You seem to have difficulty thinking in terms of abstract symbols (m_A, F_ext, ...), and always seem to replace them with specific numbers. That
    is a HUGE limitation in your mental processes. Note that all of the laws
    of physics are phrased in terms of abstract symbols, including Newton's
    three laws.

    the newtone assumes not existent forces in gravity, and most probably he
    was gay, particularly, to a vast extent.

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