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Are fictitious forces necessary to solve certain problems?

 
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Nov3-11, 09:20 AM   #69
 

Are fictitious forces necessary to solve certain problems?


Quote by D H View Post
There you go then. This is the source of your confusion. In Newtonian mechanics, coordinate acceleration and fictitious forces are essentially same thing, sans a factor of mass. The net fictitious force is simply coordinate acceleration times mass.
You mean your confusion.
But indeed, this seems to be largely a matter of words! In Newtonian mechanics as well as most textbooks (including the one that you directed me to by means of Google), coordinate acceleration exists due to Newtonian ("real") forces, and no fictitious force concepts are introduced at all.

Quote by DaleSpam View Post
[..]What one does not have to do is to stick a big label on them and say "this term here is a fictitious force". The appropriate terms in the equations of motion represent fictitious forces whether or not they are explicitly labeled as such.
What you call "fictitious force", others might call an artifact or correction term for non-inertial motion; and although mathematically the value will be the same, conceptually that is very different. So, it's not merely a matter of labels, but also of concepts. Perhaps that is why some teachers can get very upset when others call those correction terms "fictitious forces".

Anyway, as commonly textbooks do not use the fictitious force concept for those derivations, I take it that my question has been sufficiently answered.

Thanks for the feedback!
Nov3-11, 09:53 AM   #70
 
Quote by harrylin View Post
coordinate acceleration exists due to Newtonian ("real") forces, and no fictitious force concepts are introduced at all.
In general coordinate acceleration depends on the net force, which is the sum of all forces that might act: interaction and inertial.
Nov3-11, 03:08 PM   #71
 
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Quote by harrylin View Post
What you call "fictitious force", others might call an artifact or correction term for non-inertial motion; and although mathematically the value will be the same, conceptually that is very different. So, it's not merely a matter of labels, but also of concepts. Perhaps that is why some teachers can get very upset when others call those correction terms "fictitious forces".
It doesn't matter if you also call it an "artifact" or a "correction term" or "Bob's uncle". It fits the definition of a fictitious force therefore it is a fictitious force, regardless of what other definitions it also fits.

Your argument here is like saying that a square is not a rectangle because other people will call it a square, and it isn't just a matter of labels since squares and rectangles are conceptually different, and some people get upset if you call a square a rectangle. It is an invalid argument. A square is a rectangle because it fits the definition of a rectangle, and the extra terms in the equations of motion in a non-inertial frame are fictitious forces because they fit the definition of a fictitious force.

Quote by harrylin View Post
Anyway, as commonly textbooks do not use the fictitious force concept for those derivations, I take it that my question has been sufficiently answered.
Kindly back up this claim with a reference. All textbooks should use fictitious forces, either as a part of the derivation or as an end result of the derivation. If they do not, then they are in error. Obviously, they may not discuss their use of fictitious forces, but they must use them.
Nov4-11, 04:34 AM   #72
 
Quote by DaleSpam View Post
[..]
Kindly back up this claim with a reference. All textbooks should use fictitious forces, either as a part of the derivation or as an end result of the derivation. If they do not, then they are in error. Obviously, they may not discuss their use of fictitious forces, but they must use them.
Already given and commented in post #65; similar to basic textbooks that discuss Coriolis acceleration etc. without introducing the fictitious force concept. It was in that sense that I intended my question, which now has been answered to my satisfaction.
Nov4-11, 05:29 AM   #73
D H
 
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Quote by harrylin View Post
Already given and commented in post #65; similar to basic textbooks that discuss Coriolis acceleration etc. without introducing the fictitious force concept. It was in that sense that I intended my question, which now has been answered to my satisfaction.
Coriolis acceleration and coriolis force are one and the same thing, sans a factor of mass. You are playing a stupid semantics game, Harald.

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centrifugal, coriolis, fictitious forces, inertial, weather
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