What's new
What's new

# Centripetal Force

#### bkeats

##### Plastic
Hi All,
Can someone tell me what Centripetal Force means? I saw it recently used in conjunction with the operation of a lathe chuck.

Cheers,
Brent

#### Red James

##### Stainless
Hi All,
Can someone tell me what Centripetal Force means? I saw it recently used in conjunction with the operation of a lathe chuck.

Cheers,
Brent
Centripetal Force is the force required to exactly balance the Centrifugal force created by rotating an object around a center point. A moon is forced into a "circular" path around a planet by centripetal force from gravity ... balanced by the centrifugal force of rotating around the planet. Centripetal means "center directed". It is common to describe the rock on a string whirling around as being confined by centrifugal force, but it is really centripetal force. The centrifugal force is what pushed the rock out against the string.

The spinning lathe chuck jaws are pushed outward with centrifugal force. The scroll of the chuck applies the centripetal force to keep the jaws from flying out. This concept is more confusing than it is worth. . . just say centrifugal force and everyone knows what you mean.

#### angelw

##### Diamond
The spinning lathe chuck jaws are pushed outward with centrifugal force. The scroll of the chuck applies the centripetal force to keep the jaws from flying out. This concept is more confusing than it is worth. . . just say centrifugal force and everyone knows what you mean.

Hi Red,
The so called Centrifugal Force, is not an actual force, but implied at best. With the Rock and String example, its true that the string exerts the Centre Seeking (Centripetal) force on the rock. At the moment the string breaks, the rock leaves the circular path in a dead straight line, tangent to the circular path being forced upon it. Accordingly, its inertia that rules the path once the Centripetal force is removed. Centrifugal Force could be defined as Zero Centripetal Force.

The chuck jaws are wanting to travel in a straight path. There is no force making the jaws deviate from this straight path away from chuck centre (Centre Fleeing as is the literal meaning of Centrifugal).

Regards,

Bill

#### 706jim

##### Stainless
More spcifically, it refers to the tendency of hydraulic chucks to open up at high rpm's as their gripping force is reduced by centrifugal (or centripital) force.

#### sfriedberg

##### Diamond
CentriFugal flings things outward.
CentriPetal pulls things inward.

#### angelw

##### Diamond
CentriFugal flings things outward.
CentriPetal pulls things inward.

Except there is no outward flinging going on.

If you were sitting in a car, on the seat, and the vehicle accelerated in a straight path forward, you would be pressed against the back of the seat. But there's no force pushing you towards the back, it's just your inertia resisting the back of the seat pushing towards you. And that's all "centrifugal force" is - when the vehicle is cornering, the passenger feel as though they are being flung outward - but there's no force flinging the passengers in an outward direction at all. Its Centripetal force being provided by the friction between the vehicle tires and road, and in turn, between passenger and seat, or passenger restraint by seat belt, or the push of the door against the passenger. In all cases, the passenger wants to keep moving in a straight direction, tangent to the circular path being forced upon the vehicle and passengers. The feeling of being flung outward is just the passenger's inertia resisting the Centripetal force being applied.

Regards,

Bill

#### metaltech

##### Hot Rolled
Spot on, Bill. Well said. (As usual.)

#### sfriedberg

##### Diamond
My posting was intended as a short mnemonic aid, not a freshman physics lecture on inertia and acceleration. Thank you for providing same.

#### angelw

##### Diamond
My posting was intended as a short mnemonic aid, not a freshman physics lecture on inertia and acceleration. Thank you for providing same.

Well then, it could more accurately be:
CentriFugal is a fictitious force, as its referred to, not an applied force.

Regards,

Bill

Last edited:

#### sfriedberg

##### Diamond
Bill, I don't intend to get into a pissing contest, but you need to think about rotating frames of reference before calling centrifugal forces fictitious.

#### HuFlungDung

##### Diamond
Why are people so cowardly about pissing contests, anyways? If no one ever wants to get into a pissing contest, someone, somewhere, at sometime, most certainly did want to get into a pissing contest, and hence, he proposed it

#### CalG

##### Diamond
Bill, I don't intend to get into a pissing contest, but you need to think about rotating frames of reference before calling centrifugal forces fictitious.

Frames of reference be damned. Inertia defines the path, real forces act to modify the path

There is NO single FORCE that causes an object to describe a curved path. ( Unless you wish to get into theoretical aspects of "curved space" )

perhaps centrifugal could be defines as a sumation effect. But it is not a "force".

It is a term in common use however, so perhaps that too will change.

#### angelw

##### Diamond
Bill, I don't intend to get into a pissing contest, but you need to think about rotating frames of reference before calling centrifugal forces fictitious.
Yes, I understand that, and I'm not the instigator of "fictitious" with regards to Centrifugal force; it is what it is.

I understand that in a rotating frame of reference the objects appears to accelerate away from the center of rotation. However, the centrifugal force is really an inertial force, meaning that it is caused by the motion of the frame of reference itself and not by any external force. Centripetal force is a real force independent of the frame of the observer.

Regards,

Bill

#### alphonso

##### Titanium
You guys quit it. You're making my brain hurt.

#### robert123

##### Stainless
There is NO single FORCE that causes an object to describe a curved path. ( Unless you wish to get into theoretical aspects of "curved space" )

Doesn't gravity cause the planets to follow curved paths around the sun?

#### Heavey Metal

##### Banned
What dum as put tires and a seat on your chuck?

The observed force wanting to open your chuck jaws is ?

''Centrifugal Force could be defined as Zero Centripetal Force''. So what the fuck is holding your chuck jaws on did you forget the bolts?
Except there is no outward flinging going on.

If you were sitting in a car, on the seat, and the vehicle accelerated in a straight path forward, you would be pressed against the back of the seat. But there's no force pushing you towards the back, it's just your inertia resisting the back of the seat pushing towards you. And that's all "centrifugal force" is - when the vehicle is cornering, the passenger feel as though they are being flung outward - but there's no force flinging the passengers in an outward direction at all. Its Centripetal force being provided by the friction between the vehicle tires and road, and in turn, between passenger and seat, or passenger restraint by seat belt, or the push of the door against the passenger. In all cases, the passenger wants to keep moving in a straight direction, tangent to the circular path being forced upon the vehicle and passengers. The feeling of being flung outward is just the passenger's inertia resisting the Centripetal force being applied.

Regards,

Bill

#### angelw

##### Diamond
1. What dum as put tires and a seat on your chuck?

2. The observed force wanting to open your chuck jaws is ?

3. So what the fuck is holding your chuck jaws on did you forget the bolts?

1. Its called an analogy.
2. Inertia.
3. Centripetal Force.

#### Heavey Metal

##### Banned
Was that you or your evil twin that said this

"Centrifugal Force could be defined as Zero Centripetal Force"

How do you machine an analogy (do you have a print that you can share?)

1. Its called an analogy.
2. Inertia.
3. Centripetal Force.

#### angelw

##### Diamond
Was that you or your evil twin that said this

"Centrifugal Force could be defined as Zero Centripetal Force"

How do you machine an analogy (do you have a print that you can share?)

Wow, what an absolutely slick comeback.

Replies
41
Views
2K
Replies
9
Views
544
Replies
24
Views
2K
Replies
14
Views
379
Replies
1
Views
319