Centrifugal force and gravity the same?

[Ringer]

I thought that gravity was actually displaced spacetime pushing on us, not the earth pulling on us.

Yup, you're right. It's the warping of space time based on the density of the object. Nonetheless it is a force and that force has a vector. Straight to the CG of the object.

 

[Ringer]

If I understood Jorgenson correctly, in an efficient swing, the hands do slow down. You don't necessarily slow them down deliberately - but as the wrist-cock angle opens out there is a transfer of momentum from arms to club. If the hands don't slow down whilst the wrists uncock, then it can only be because you are simultaneously applying force to the hands, but they are accelerating less than they would if the wrist angle remained constant, again due to the transfer of momentum to the club.

However, I am sure that in a real swing, we intuitively time and sequence our effort and movement in order that the clubhead can pass the hands relatively smoothly without jarring or straining the wrists, given their natural range of movement. If this requires some adjustment to a theoretical model swing, then I am sure that it'll happen subconsciously, on pain of...pain.

Agree completely. But where does the slow down happen? In all of the swing models I have seen where only gravity is used, the slow down happens VERY early. No where near where we observe it in the golf swing. I think the hands slow down, but I believe they accelerate far longer than one can account for to say that the clubhead is going to flail from it and create our alignments for us.

We'd have to ask Dr. Zick to do the modeling for us to find out for sure.

 

[SteveT]

Yup, you're right. It's the warping of space time based on the density of the object. Nonetheless it is a force and that force has a vector. Straight to the CG of the object.

Since a 'vector' has magnitude and direction, can you tell us what is the direction the gravitational force vector that goes "straight to the CG of the object"?

Why do you avoid acknowledging and answering that question ... unless you don't know ..?!

 

[Ringer]

Ringer ... have you followed my instructions, or are you just hiding from reality because you have assumed that the force of gravity applies or can be applied in a diagonal direction to create a centrifugal 'pull' .... now that concept would reinvent 'Gravity' ... but hey, it's 'golf' where anything goes ....

I don't usually listen to crass and abrasive people as a general rule, so no. I don't follow your instructions.

 

[SteveT]

I don't usually listen to crass and abrasive people as a general rule, so no. I don't follow your instructions.

I was trying to be humorous, but if you took that as 'crass and abrasive', then I apologize. If that's inadequate, then remain in your ignorance ...!

 

[Ringer]

I was trying to be humorous, but if you took that as 'crass and abrasive', then I apologize. If that's inadequate, then remain in your ignorance ...!

Then I take it back. Just didn't get that it was meant as humorous.

 

[islandgolf629]

The more golf science I hear, the more I think that the greatest genius in the game has got to be Bobby Jones.

How about "most important things to watch in the leg movement...as the club nears the ball, the legs should be ready to produce the upward thrust that means so much in power"?

He probably wrote that 50 years ago.

Bobby Jones had a degree in engineering.

 

[SteveT]

Then I take it back. Just didn't get that it was meant as humorous.

Didn't you notice the :wink: smilie ...???

If I understand you correctly, you believe in a gravitational centrifugal pull, and if I was correct, I tried to help you feel the sum total of gravitational force on the golfswing ... it's the same whether it's in a dynamic or static state.

Before I explained it to you, I wanted you to feel and understand where I was leading you. If I was wrong, then I expected you to correct me.

You invoked F = ma ... but applying that to gravitation only, it becomes: W = -mg ... where W = weight, m = mass and g = acceleration due to gravity ... since gravity sucks everything down and vertical only ... no diagonal gravitational force in the plane of a golfswing. Do you appreciate that?

Now if I'm resonating with you, go back and hold your Driver in a static Impact position ... and that's the sum of the gravitational force on your arms and club ... and it's called "weight".

 

[islandgolf629]

Wait!!!! Everyone is forgetting the Normal force.

 

[SteveT]

Bobby Jones had a degree in engineering.

Yes he was ... but he never tried to impose his technical knowledge in his writings or films. What he did do was carefully describe the hickory shafted golfswing in clear and concise term, which reflected his B.A. degree in English literature and legal training. I marvel when I read his books.

 

[natep]

Either you're "pretty" or you must be "sure" ... because we're slinging scientific sh!t all over now and nobody can seem to make any of it stick ...

Seriously, I would think that the rotating left shoulder is the primary generator of centripetal force around an established pivot .. somewhere between your shoulders and closer to your left shoulder according to SPS.

The Parametric Acceleration is created by an EXTRA force according to Miura, and all I'm asking those who depend on PA to tell me how it's applied within the golfswing.

So far I see no specific reply.

LOL yes this thread had drifted from diagonal gravity to quantum existence and general relativity.

I said pretty sure because I hadn't read the link and was unsure of the true definition of parametric acceleration.

Now that I have confirmed that I understand it I can assure you that I do this intentionally by pulling my left shoulder diagonally up away from the ball as quickly as possible just before impact.

It probably happens naturally to some extent in any decent swing but I really emphasize the motion when I am looking for maximum distance.

 

[SteveT]

@ natep ... I suggest you read and study the link here:

Parametric acceleration – the effect of inward pull of the golf club at impact stage - Miura - 2001 - Sports Engineering - Wiley Online Library

... because my understanding is that Miura is saying an additional 'parametric acceleration' added to the normal 'centrifugal'(shudder) force will increase the overall kinetic energy ... which makes sense.

Your shoulder rotation is just for 'centripetal' force generation ... and that still leaves the mysterious 'parametric acceleration' to account for .... can you find it anywhere in the golfswing ..??!!!

 

[natep]

No, I don't believe that I can. He seems to be saying the pivot point is moved in the direction of the centripetal force before impact. I don't know if the pivot point is the left shoulder, the hands, or the top of the spine.

I wish I could read the article.

 

[islandgolf629]

No, I don't believe that I can. He seems to be saying the pivot point is moved in the direction of the centripetal force before impact. I don't know if the pivot point is the left shoulder, the hands, or the top of the spine.

I wish I could read the article.

PM me your e-mail, I have the whole PDF file.

 

[Virtuoso]

Ok, in order for the clubhead to pass the hands, it would have to travel at a faster RPM than the hands. That's tough to do especially when you consider the hands have a shorter circumference to cover. So you either have to apply a torque to the club that accelerates it, or slow down the hands (you could also change the velocity of the hands inward - parametric acceleration). Now, as the arms get extended they slow down sure, but if I remember correctly (and I will have to do some checking up to verify) the hands do not slow down until just shy of impact. Not nearly enough time from when they slow down to impact to account for the clubhead flail around the wrists.

There is plenty of time.

 

[Ringer]

On a body forced to move in a circle, there must be a centripetal force (a force directed toward the centre of the circle).

On a body forced to move in a circle, there is no centrifugal force, when viewed from an inertial frame.

An inertial observer, applying the inertial laws of motion, measures no centrifugal force on a body forced to move in a circle.

An observer forced to move in a circle (and therefore non-inertial) can apply the inertial laws of motion only by adding a "fictitious" centrifugal force to the physical forces.

-----

The Principle of Equivalence (the basis of Einstein's General Theory of Relativity) says that anyone can be a valid observer, but that the inertial equations of motion may have to be adjusted to introduce imaginary (non-physical) forces.

Centrifugal force on a body is such a non-physical force.

In particular, a rotating observer invents an imaginary (non-physical) centrifugal force to explain why objects appear to move round him.

"Centrifugal" means "away from the centre" … it comes from the Latin word fugo (I flee) … as does "refugee". It is the opposite of "centripetal", which means "toward the centre" (and comes from the Latin word peto, I seek … as does "petition").

On an object moving in a circular path, there is no centrifugal force as viewed by an inertial observer.

Centrifugal force on such an object only exists for non-inertial observers.

However, both inertial and non-inertial observers recognise a centrifugal force from such an object, on whatever is keeping it in the circle.

Two different meanings:

Most standard physics textbooks use the "modern" meaning of centrifugal force as a pseudoforce, existing only as an artefact of viewing things in a non-inertial frame.

It is not a "real" (physical) force, since it has no agent.

The "old-fashioned" meaning of centrifugal force as the Newton's-3rd-law pair ("reaction force") of the centripetal force is completely "real", in any frame.

These two different types of centrifugal force act on different bodies.

Whirling on a string:

An observer holding onto a string which is whirling him in a circle feels a force along his arm toward the centre of the circle.

However, he knows that he is not moving toward the centre.

So he also feels a force in the opposite direction, balancing the force along his arm.

In that sense, he genuinely feels a centrifugal force.

In a turning car:

The driver of a car turning sharply left notices that unsecured objects slide to the right … away from the centre of the turn.

In the driver's rotating (non-inertial) frame of reference, that can only be explained by a force to the right.

It is a centrifugal force, acting on everything in the car, but nothing physical is causing it.

If the driver regards that force as real, then he may apply the inertial laws of motion.

centrifugal force

 

[Burner]

And then there was this..........................

centrifugal force

Article_11 Centrifugal Force

 

[natep]

Nice find.......and so it continues......

 

[dbl]

That article 11 was way too long for whatever value it (may or may not) have.

Just define your frame of reference and then you can know whether centifugal forces are at work.

 

[ej20]

That article 11 was way too long for whatever value it (may or may not) have.

Just define your frame of reference and then you can know whether centifugal forces are at work.

Yeah...everything is relative is it not?

I'll side with Ernst Mach and Albert Einstein any day over Ethan Skyler(who??).