The discussion revolves around the forces acting on a stone in a sling, particularly focusing on whether the force exerted by the stone on the rope is "centrifugal" or "centripetal," and whether these forces are "real" or "apparent." The scope includes theoretical considerations of forces in rotating frames of reference and the distinctions between different types of forces.
Participants express differing views on the nature of the forces involved, with no consensus reached on whether the force exerted by the stone is centrifugal or centripetal, or whether it is real or apparent.
Participants reference various definitions and concepts related to forces, but there are unresolved distinctions regarding the classification of forces in different frames of reference, particularly between real and fictitious forces.
Luigi Fortunati said:Is the force of the stone on the rope "centrifuge"?
Is the force of the stone on the rope "real" or "apparent"?
The strength of the stone on the rope of the sling.PeroK said:What force, what stone, what rope?!
The terms that I learned are "centrifugal" and "fictitious".Luigi Fortunati said:Is the force of the stone on the rope "centrifuge"?
Is the force of the stone on the rope "real" or "apparent"?
jbriggs444 said:The terms that I learned are "centrifugal" and "fictitious".
Centrifugal: Literally meaning "directed away from the center".
Centripetal: Literally meaning "directed toward the center".
Real force: An ordinary physical force. It is present regardless of what reference frame is used. Real forces have third law partner forces.
Fictitious force: A force that is invented to allow Newton's second law to apply in an accelerated or rotating frame of reference. Fictitious forces do not have third law partner forces.
In the case of a stone being whirled in a sling there are three forces that may be considered.
1. Centripetal force. This is the real force of the sling on the stone. It is called "centripetal" simply because it is directed toward the center. https://en.wikipedia.org/wiki/Centripetal_force
2. Centrifugal reaction force. This is the real force of the stone on the sling. It is the third law partner force to the centripetal force. https://en.wikipedia.org/wiki/Reactive_centrifugal_force
3. Centrifugal force. This is the fictitious force. If one adopts a frame of reference that rotates with the sling then the stone is stationary. Yet it is still subject to the real centripetal force. In order to explain how it can remain motionless one invents a "centrifugal force". https://en.wikipedia.org/wiki/Centrifugal_force
By "slingshot", you mean the Y-shaped device with rubber bands that boys use to shoot projectiles? And not the leather strap-and-pouch device that David used to slay Goliath?Luigi Fortunati said:Ok, if I understand correctly, there exists the "real" centrifugal force and there is also the "apparent" centrifugal force.
However, in the case of the slingshot, there are no "apparent" forces, right?
jbriggs444 said:By "slingshot", you mean the Y-shaped device with rubber bands that boys use to shoot projectiles? And not the leather strap-and-pouch device that David used to slay Goliath?
Luigi Fortunati said:However, in the case of the slingshot, there are no "apparent" forces, right?
Luigi Fortunati said:Whirling sligshot, not Y-shaped device
jbriggs444 said:There is indeed an apparent force. It is the centrifugal force on the stone that appears to hold it in place in the sling as it is whirled. It is a fictitious force -- it only appears if we consider the stone to be "in place".
By considering the stone to be "in place", at rest in the sling we have implicitly adopted the rotating frame of reference where the sling is at rest.
jbriggs444 said:There is indeed an apparent force. It is the centrifugal force on the stone that appears to hold it in place in the sling as it is whirled. It is a fictitious force -- it only appears if we consider the stone to be "in place".
By considering the stone to be "in place", at rest in the sling we have implicitly adopted the rotating frame of reference where the sling is at rest.
The force that holds the stone in place against the inward/centripetal force is outward/centrifugal.Luigi Fortunati said:If it appears to "hold it" it is a "centripetal" force, not "centrifugal"!