Re: Confusion redux: "Centrifugal Force"

Mike wrote:
Paul B. Andersen wrote:
Mike wrote:
Tom Roberts wrote:
Mike wrote:
Tom Roberts wrote:
When I whirl a stone on a string around my head, the centripetal force
is the inward force of string tension on the stone, and the reaction to
the centripetal force is the outward force of string tension on my hand.
I would like to inform you that this force is what we call a
centrifugal force.
That's your problem right there -- this most definitely is NOT
"centrifugal force". This is a force of TENSION IN THE STRING. The
"centrifugal force" acts ON THE STONE, not on my hand. <shrug>
if you have both the centrifugal force and the centripetal force acting
on the stone then the stone does not move. In the inertial reference
frame, the centrifugal force acts on the hand and IT IS the tension on
the spring and that is why it is measurable.
There is but one force acting on the stone, and that is
the centripetal force acting towards the centre.
That is why the stone is accelerating towards the centre!
F = ma, F and a are vectors.

In the rotating frame, a force must be added to the stone to explain
the apparent motion. This JUST happens to be equal to the reaction
force, the centrifugal force.
In the rotating frame, the stone is NOT moving despite the fact
that a centripetal force is acting on it. That's why a pseudo force
must be added to the stone to explain the apparent LACK of motion.

You must review your mechanics dusted notes.

For an observer on a rotating table there is a measured force on the
ball or stone but he does not see any motion. Thus the observer
includes that besided the force measured by the spring there must be
another, equal and opposite force acting on the ball. Now, get this
well in your mind or review you notes:

- the force acting on the spring is the centrifugal force and it
extends it.

No, it is the reaction force to the centripetal force that
is extending the spring.

When you pull the spring, the spring exerts a force on
the stone, and this force is acting toward the centre.
The centri_petal_ force.


- the force acting on the ball is the centripetal force in the inertial
frame and just a force equal to the centripetal in the rotating frame

- the force that must be added to the ball to explain the state of rest
in the rotating frame is equal to the centrifugal force in both
magnitude and direction.

Right.
Since there is only one real force acting on the ball,
the centripetal force, the ball should be accelerating towards
the centre. But since it apparently isn't, a non real pseudo
force has to be added to the ball, acting away from the centre,
the centri_fugal_ force.

Thus, in the rotating frame this added force is better to be called an
inertial force but in the inertial frame the centrifugal force is real,
measurable and has an observable effect: IT EXTENDS THE SPRING.

No.
Look:

ball /\/\/\/\/\ hand you
<--|--> <--|-->
F1' F1 F2 F2'

F1 is the force acting on the ball - towards you
F1' is the force acting on the spring - outwards
F2 is the force acting on the hand - outwards
F2' is the force acting on the spring - towards you

F1' and F2' are the forces stretching the spring.
F1 is the only force acting on the ball.

Accelerate the ball linearly by pulling the spring.
There is but one force acting on the ball: the force F1 that
is accelerating it. The force you, via the spring, are exerting on
the ball is acting towards you - that's why the ball is accelerating
towards you. F1 = ma. F1 is the _only_ force acting on the ball.
Of course there is a reaction force F2 which exerts a force on your
hand, and this force is acting towards the ball.
_But this force is not acting on the ball_.

The case when the force on the ball is perpendicular to its
velocity is no different. There is but one force acting on
the ball. It is acting in the same direction as the acceleration
- towards the centre - centripetal.

This is basic stuff. if you do not understand it there is a big problem
with the education quality you received. You must ask your money back
from the institution you attended and go attend the course again.

It's mercy in the fact that your ignorance prevent you from
understanding how pathetic this statement is from one who obviously
lack basic education in physics.

Ignorance of own ignorance is the worst kind of ignorance.

How confused can you get?

I was told once that insane people in mental institutions claim that
everyone alse out there is crazy, not them.

That should make you think.
You claim that everyone else is wrong, not you.

Paul
.

Relevant Pages

  • Re: Confusion redux: "Centrifugal Force"
    ... "centrifugal force". ... There is but one force acting on the stone, ... equal and opposite force acting on the ball. ... The reaction force to the centripetal force is acting outwards, ...
    (sci.physics.relativity)
  • Re: Confusion redux: "Centrifugal Force"
    ... "centrifugal force". ... There is but one force acting on the stone, ... This JUST happens to be equal to the reaction ... equal and opposite force acting on the ball. ...
    (sci.physics.relativity)
  • Re: Confusion redux: "Centrifugal Force"
    ... "centrifugal force". ... There is but one force acting on the stone, ... This JUST happens to be equal to the reaction ... equal and opposite force acting on the ball. ...
    (sci.physics.relativity)
  • Re: Confusion redux: "Centrifugal Force"
    ... "centrifugal force". ... on the stone then the stone does not move. ... There is but one force acting on the stone, ... In the rotating frame, the stone is NOT moving despite the fact ...
    (sci.physics.relativity)
  • Re: Confusion redux: "Centrifugal Force"
    ... If the spring is attached to a ball in stead of the wall, ... inertial reference frame. ... definition of centrifugal force. ... move away from the center of rotation. ...
    (sci.physics.relativity)