I'm interested in the general formula in terms of a position vector velocity and inner products, without reference to any coordinates.

I am high school student. I want to read the articles of famous scientists. These articles must be in their original language and not edited in any way. For example, I want to read Special Relativity, which was published by Einstein in 1905. In the German language and with an exact copy from 1905...

I know this sounds elementary; that is why it has taken me this long to ask this question. I understand how forces can be added this way. But I don't see how it can be added in this way