Goldstein classical mechanics discrepancy?

Click For Summary
Goldstein's text states that friction or dissipative forces are never conservative because the dot product of force and displacement is always positive. However, it is argued that most frictional forces act opposite to displacement, leading to negative dot products. This raises the question of whether the statement should instead indicate that these forces are never conservative since the dot product is always non-zero. Other classical mechanics texts echo similar sentiments, suggesting a common misunderstanding. The discussion highlights a potential error in Goldstein's wording regarding the nature of work done by friction.
Syrus
Messages
213
Reaction score
0

Homework Statement



In Goldstein's text, he discusses conservative fields and then states that "friction or dissipative forces are never conservative since F dot ds is always positive."

From what I recall, most frictional interactions occur in directions opposite the displacement, and would, hence, result in negative values of the dot product. Shouldn't, then, the text read isntead: friction or dissipative forces are never conservative since F dot ds is always non-zero?

I have checked a few other classical mechanics texts and they all seem to have statements along the same lines- so I feel there is a detail I am missing here.

Homework Equations


The Attempt at a Solution

 
Physics news on Phys.org
I still have my 1st edition of Goldstein that I used in a course 42 years ago. I found the quote on page 3 and lo and behold I see that I had circled the word "positive" and added a question mark in the margin! I think Goldstein meant to use the word "negative" here (even though you can construct scenarios where a force of friction does positive work).
 
That's remarkable TSny, thanks for checking!
 

Similar threads

  • · Replies 16 ·
Replies
16
Views
4K
  • · Replies 33 ·
2
Replies
33
Views
7K
  • · Replies 1 ·
Replies
1
Views
3K
  • · Replies 4 ·
Replies
4
Views
7K
  • · Replies 3 ·
Replies
3
Views
3K
Replies
7
Views
6K
  • · Replies 14 ·
Replies
14
Views
2K
  • · Replies 9 ·
Replies
9
Views
3K
  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 7 ·
Replies
7
Views
3K