B The force of the stone on the rope

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The discussion centers on the forces acting on a stone in a sling, specifically whether these forces are "real" or "apparent." The centripetal force exerted by the sling on the stone is classified as a real force, while the centrifugal force, which appears to act outward when viewed from a rotating frame of reference, is considered a fictitious force. Participants clarify that the centrifugal force is not an actual force but rather an apparent force that arises when the stone is perceived to be at rest in the sling. The conversation also distinguishes between the terms "centrifugal" and "centripetal," emphasizing their definitions and roles in the context of motion. Ultimately, the discussion highlights the complexities of force perception in rotating systems.
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Is the force of the stone on the rope "centrifuge"?

Is the force of the stone on the rope "real" or "apparent"?
 
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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 rope sling
 
What force, what stone, what rope?!
 
PeroK said:
What force, what stone, what rope?!
The strength of the stone on the rope of the sling.
 
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 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
 
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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

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?
 
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?
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?

Edit: If so, then we are considering the linear motion of a projectile as it is released and is accelerated under the force of the rubber bands. It rests on a pad during this acceleration phase. If one adopts a frame of reference where the stone is at rest while being accelerated then a rearward fictitious force can be considered. It explains why the stone is judged to be at rest [in this reference frame] while still experiencing the real force from the pad. https://en.wikipedia.org/wiki/Fictitious_force
 
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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?

Whirling sligshot, not Y-shaped device.
 
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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

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.
 
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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.
 
  • #11
If it appears to "hold it" it is a "centripetal" force, not "centrifugal"!
 
  • #12
Luigi Fortunati said:
If it appears to "hold it" it is a "centripetal" force, not "centrifugal"!
The force that holds the stone in place against the inward/centripetal force is outward/centrifugal.
 

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