sparrowhawk

I'm an engineering graduate student studying for my PhD qualifying exams. One part of the exam includes questions on classical physics (from a physics perspective not engineering).

So I rented a copy of Classical Mechanics by Marion, and Thornton and was reading it when I came across the statement "Newton’s third law does not apply to velocity dependent forces." The author left no explanation. I have never heard this before and was wondering if any one has heard a good explanation, or knows of some good examples of why this is true.

The only examples of velocity dependent forces that I can think of involve fluids (like air resistance) of fields (like the Lorentz force) and these situations can be some complex that it’s hard for me to see if and how the law is violated.

Note that this statement applies to classical physics so I am NOT looking for an explanation that involves relativity or quantum physics. Usually I would ask a professor but I'm out of town for a while.