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David Smith
11-25-2005, 11:34 PM
Hi all

I wondered how many use the D'Alembert principle that changes Newton's F=MxA to F-MxA=0 and so by taking account of (some say virtual) inertial forces all dynamic analysis becomes the same as static analysis.

I have found that some find it (D'Alemberts Principle) difficult to accept, because they don't see how equilibrium can exist when there is acceleration, yet I find it makes analysis more simple and clearer to visualise positive and negative forces and moments.

How valid is it to argue that in any mechanical system, including those in motion, all forces and moments are in equlibrium.

I would appreciate any opinions.

Thanks DeeKay