(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

If anyone is familiar with (or has nearby) Goldstien's Mechanics text, I am having some difficulty seeing why equation 1-34 is true.

Can someone explain or perhaps hint as to why, in the given context, the gradient of a potential function of distance (in terms of a difference of position vectors) equals the difference in position vectors times an arbitrary scalar function?

Perhaps I should also lay out some other inquiries I had regarding this discussion:

Part of Goldstein's development of the internal potential energy for a system of a system of particles is motivated by "sasifying the strong law of action and reaction." Is this satisfaction a necessary feature of conservative fields, or he is simply doing this because many typical fields satisfy this criteria? (page 10 of edition 2)

2. Relevant equations

3. The attempt at a solution

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# Homework Help: Difficult equation to understand in Goldstein's Mechanics

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