## Foucault pendulum - the physics and maths involved

I have been looking at this paper (http://www.phys.unsw.edu.au/~jw/pendulumdetails.html) on the details of Foucault's pendulum. I am interested in understanding the details, but am having some trouble. My purpose is to study this as an example of how the analysis is done. I'd like to ask some questions and then plod along on my own, until the next question.

Let me start with this question. In the paragraph above equation (2) Wolfe has the equation: r" = r"p − r"o. I see where he then derives equation (2). However, it is equation (3) with which I am having a problem.

r" = r"p − r"o, which can be expanded to
mr" = mr"p − mr"o. Equation (1) is substituted for mr"p and equation (2), multiplied by m, is substituted for mr"o.

Why in equation (3) does the last term not have a minus sign?

Thanks.

Thomas

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 Quote by Thomas2054 Why in equation (3) does the last term not have a minus sign?
I haven't looked it over too closely, but I suspect that the RHS of (2) is missing a minus sign.