I have to find the equations of motion(adsbygoogle = window.adsbygoogle || []).push({}); using Newton's lawsfor this system (see attached file). I have found them using Lagrange's equations and compared with a friend's results: we have the same.

[tex]m_1 (\ddot{x_1} - \ddot{x}) + k_1 x_1 = 0[/tex]

[tex]m_2 (\ddot{x} + \ddot{x_2}) + k_2 x_2 = 0[/tex]

[tex]m_1(\ddot{x} - \ddot{x_1}) + m_2 (\ddot{x} + \ddot{x_2}) + m_3 \ddot{x} = 0[/tex]

But how do we arrive to that with Newton's laws? Why isn't it simply [itex]m_1 \ddot{x_1} + k_1 x_1 = 0[/itex] for [itex]m_1[/itex] ?!

eee.. I should have posted this in the homework help section, I apologize.

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# Homework Help: Setting the equ. of motion help

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