# How does Newton's 1st Law impact centrifugal force? Does it exist?

• physicsfan101
In summary, the conversation discusses the concept of centrifugal force and its existence. It is stated that centrifugal force does not exist in an inertial frame of reference, but it can be observed and explained in a non-inertial frame of reference by introducing fictitious forces. The concept is then applied to explain the phenomenon of water being removed from clothes in a washing machine during the spin cycle. f

#### physicsfan101

New user has been reminded not to change their OP after others have responded to it
Homework Statement
Some people claim that water is removed from clothes in a washing machine by centrifugal force throwing the water outward. Is this correct? Explain in terms of Newton's 1st Law.
Relevant Equations
none
The reading that I have says that centrifugal force (center fleeing) does not exist

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Homework Statement:: How does Newton's 1st Law relate to centrifugal force?
Relevant Equations:: none

It doesn't exist, right?
Welcome to PF.

Homework Statement:: How does Newton's 1st Law relate to centrifugal force?
Relevant Equations:: none

It doesn't exist, right?
It exists as a useful concept. Read up on frames of reference.

PeroK
It exists as a useful concept.
Like the Electromagnetic Field!

Welcome to PF.

Homework Statement:: How does Newton's 1st Law relate to centrifugal force?
Relevant Equations:: none

It doesn't exist, right?
The statement of the problem, as you posted it, asks, "How does Newton's 1st Law relate to centrifugal force?". Whether centrifugal force exists is immaterial to your answering the question.

Suppose one changed things around somewhat and asked "How do children's expectations around Christmas time relate to Santa Claus?", would you proceed to answer the question or would you express your doubts that Santa Claus exists?

PeroK
The statement of the problem, as you posted it, asks, "How does Newton's 1st Law relate to centrifugal force?". Whether centrifugal force exists is immaterial to your answering the question.

Suppose one changed things around somewhat and asked "How do children's expectations around Christmas time relate to Santa Claus?", would you proceed to answer the question or would you express your doubts that Santa Claus exists?
So how would you answer the question?

Welcome to PF.

The reading I have says "centrifugal force (center fleeing) does not exist. It is the apparent force that an object moving in a circle perceives as a result of its inertia".

So how would you answer the question?
I would think of a physical observation that is a manifestation of Newton's 1st law in one frame of reference and a manifestation of centrifugal force in another frame of reference.

Homework Statement:: Some people claim that water is removed from clothes in a washing machine by centrifugal force throwing the water outward. Is this correct? Explain in terms of Newton's 1st Law.
Relevant Equations:: none

The reading that I have says that centrifugal force (center fleeing) does not exist
I see you changed the original statement of the problem to something different. Now it's asking if it the claim by some people that water is removed from clothes in a washing machine by centrifugal force throwing the water outward is correct. That is exactly an example of what I was referring to in post #9. The physical observation is that water comes out of the wet clothes during the spin cycle. Explain this observation from (a) the frame of reference of the laundry room and (b) the spinning frame of reference of the clothes.

Another interesting observation is the case where we have a tangential accelerating force, which forces a particle to accelerate in the direction tangential to the line to a fixed central point. The particle in this case does clearly move outwards away from the origin. I.e. there is a centrifugal component of the acceleration, despite there being no direct centrifugal force.

The reading I have says "centrifugal force (center fleeing) does not exist. It is the apparent force that an object moving in a circle perceives as a result of its inertia".
Newton composed his laws on the assumption of an inertial reference frame. In such a frame, centrifugal force does not exist and an explanation using it would not be valid.
But it is perfectly fine to use non-inertial frames provided you modify Newton’s equations by introducing "fictitious" (or "virtual") forces as appropriate.
As @kuruman points out in post #10, using the reference frame of the clothes, centrifugal force exists and is responsible for driving out the water.

That Newton’s 1st law uses an inertial frame does not invalidate the centrifugal explanation.

PeroK
This cartoon says it all and merits reposting.

Reference: https://xkcd.com/123/

berkeman and PeroK