Physics debate
- Verskis
- Posts: 179
- Joined: Fri Oct 27, 2017 2:14 am
- Location: Tampere, Finland
- Ski style: XCD touring on small hills. Heavy tele at resort
- Favorite Skis: Åsnes Rabb 68
- Favorite boots: Alico Ski March
- Occupation: Hydraulics engineer
Re: Physics debate
And we are still not discussing if the cable spring generates forward momentum, of course it does not do that. But it generates force to the ski, a force that is trying to bury the ski tip in the snow.
- GrimSurfer
- Posts: 638
- Joined: Sun Dec 11, 2022 11:56 am
- Ski style: Nordic Backcountry
- Favorite Skis: Yes
- Favorite boots: Uh huh
Re: Physics debate
The forces are equal and opposite. There is no net torque. The forces cancel at the boot/binding. Nothing is transmitted to the ski other than the skier’s mass.Verskis wrote: ↑Mon Jan 02, 2023 11:50 pmNewton's 3rd law states that for every force there is an equal but opposite counterforce. That one you've got right. But now you have to learn to apply that law.
Spring is not violating the 3rd law, it is pullin the boot heel and the binding with equal but opposite forces. These forces generate torque to the boot, and the binding. Boot torque generates force to the shin of the skier (think tall plastic boots, so it is easier to mentally get the image), the skier leg is pushing against the boot with an equal but opposite force, 3rd law not violated here. The binding torque tries to rip the rearmost binding screws out of the ski, but let's assume the screws can handle that, so the ski core holds the screws with an equal but opposite force. Once again, no laws of Newton were violated.
Since the binding is screwed rigidly to the ski, the torque generated to the binding is torqueing the ski too, trying to sink the front part of the ski deeper in the snow. So ski is pushing against the snow with some force. This force of course has the counterforce, the snow is supporting the ski with an equal but opposite force. Newton can rest in his grave, we are still abiding his 3rd law when skiing.
If this were otherwise the case, you’d have a system capable of perpetual motion.
Last edited by GrimSurfer on Mon Jan 02, 2023 11:59 pm, edited 1 time in total.
We dreamed of riding waves of air, water, snow, and energy for centuries. When the conditions were right, the things we needed to achieve this came into being. Every idea man has ever had up to that point about time and space were changed. And it keeps on changing whenever we dream. Bio mechanical jazz, man.
- Verskis
- Posts: 179
- Joined: Fri Oct 27, 2017 2:14 am
- Location: Tampere, Finland
- Ski style: XCD touring on small hills. Heavy tele at resort
- Favorite Skis: Åsnes Rabb 68
- Favorite boots: Alico Ski March
- Occupation: Hydraulics engineer
Re: Physics debate
This pig is now getting tired of the wrestling...GrimSurfer wrote: ↑Mon Jan 02, 2023 11:58 pmThe forces are equal and opposite. There is no net torque. The forces cancel at the boot/binding. Nothing is transmitted to the ski other than the skier’s mass.Verskis wrote: ↑Mon Jan 02, 2023 11:50 pmNewton's 3rd law states that for every force there is an equal but opposite counterforce. That one you've got right. But now you have to learn to apply that law.
Spring is not violating the 3rd law, it is pullin the boot heel and the binding with equal but opposite forces. These forces generate torque to the boot, and the binding. Boot torque generates force to the shin of the skier (think tall plastic boots, so it is easier to mentally get the image), the skier leg is pushing against the boot with an equal but opposite force, 3rd law not violated here. The binding torque tries to rip the rearmost binding screws out of the ski, but let's assume the screws can handle that, so the ski core holds the screws with an equal but opposite force. Once again, no laws of Newton were violated.
Since the binding is screwed rigidly to the ski, the torque generated to the binding is torqueing the ski too, trying to sink the front part of the ski deeper in the snow. So ski is pushing against the snow with some force. This force of course has the counterforce, the snow is supporting the ski with an equal but opposite force. Newton can rest in his grave, we are still abiding his 3rd law when skiing.
Make a free body diagram of the system and think about it some more.
- GrimSurfer
- Posts: 638
- Joined: Sun Dec 11, 2022 11:56 am
- Ski style: Nordic Backcountry
- Favorite Skis: Yes
- Favorite boots: Uh huh
Re: Physics debate
Where does the pressure come from?
If the forces on the cable are equal and opposite, there is no torque (thrust and direction). There is only tension.
Your car’s springs are currently in tension. Look out the window. Do you see it jumping up on its own? Of course not. The mass and the resisting force are equal. The springs are in tension.
Last edited by GrimSurfer on Tue Jan 03, 2023 12:05 am, edited 1 time in total.
We dreamed of riding waves of air, water, snow, and energy for centuries. When the conditions were right, the things we needed to achieve this came into being. Every idea man has ever had up to that point about time and space were changed. And it keeps on changing whenever we dream. Bio mechanical jazz, man.
- wabene
- Posts: 716
- Joined: Sat Feb 06, 2021 9:53 am
- Location: Duluth Minnesota
- Ski style: Stiff kneed and wide eyed.
- Favorite Skis: Åsnes Gamme, Fischer SB98, Mashus M50, M78, Pano M62
- Favorite boots: Crispi Svartsen 75mm, Scarpa T4
- Occupation: Carpenter
Re: Physics debate
Hey @Verskis I meant this statement which I don't agree with.
"The forces are equal and opposite. There is no net torque. The forces cancel at the boot/binding. Nothing is transmitted to the ski other than the skier’s mass."
I agree with your statement which you will see if you read my previous post. I did attempt to delete the post you quoted because I've had enough. You locked me in though
- GrimSurfer
- Posts: 638
- Joined: Sun Dec 11, 2022 11:56 am
- Ski style: Nordic Backcountry
- Favorite Skis: Yes
- Favorite boots: Uh huh
Re: Physics debate
I have provided quite enough explanation already. I suggest you speak to somebody with a background in physics to explain all this to you. Perhaps they will be able to do so in a way you can more easily understand.Verskis wrote: ↑Tue Jan 03, 2023 12:00 amThis pig is now getting tired of the wrestling...GrimSurfer wrote: ↑Mon Jan 02, 2023 11:58 pmThe forces are equal and opposite. There is no net torque. The forces cancel at the boot/binding. Nothing is transmitted to the ski other than the skier’s mass.Verskis wrote: ↑Mon Jan 02, 2023 11:50 pmNewton's 3rd law states that for every force there is an equal but opposite counterforce. That one you've got right. But now you have to learn to apply that law.
Spring is not violating the 3rd law, it is pullin the boot heel and the binding with equal but opposite forces. These forces generate torque to the boot, and the binding. Boot torque generates force to the shin of the skier (think tall plastic boots, so it is easier to mentally get the image), the skier leg is pushing against the boot with an equal but opposite force, 3rd law not violated here. The binding torque tries to rip the rearmost binding screws out of the ski, but let's assume the screws can handle that, so the ski core holds the screws with an equal but opposite force. Once again, no laws of Newton were violated.
Since the binding is screwed rigidly to the ski, the torque generated to the binding is torqueing the ski too, trying to sink the front part of the ski deeper in the snow. So ski is pushing against the snow with some force. This force of course has the counterforce, the snow is supporting the ski with an equal but opposite force. Newton can rest in his grave, we are still abiding his 3rd law when skiing.
Make a free body diagram of the system and think about it some more.
If they manage to get through, feel free to tell your friends.
Last edited by GrimSurfer on Tue Jan 03, 2023 12:10 am, edited 1 time in total.
We dreamed of riding waves of air, water, snow, and energy for centuries. When the conditions were right, the things we needed to achieve this came into being. Every idea man has ever had up to that point about time and space were changed. And it keeps on changing whenever we dream. Bio mechanical jazz, man.
- Verskis
- Posts: 179
- Joined: Fri Oct 27, 2017 2:14 am
- Location: Tampere, Finland
- Ski style: XCD touring on small hills. Heavy tele at resort
- Favorite Skis: Åsnes Rabb 68
- Favorite boots: Alico Ski March
- Occupation: Hydraulics engineer
Re: Physics debate
Alrightwabene wrote: ↑Tue Jan 03, 2023 12:04 amHey @Verskis I meant this statement which I don't agree with.
"The forces are equal and opposite. There is no net torque. The forces cancel at the boot/binding. Nothing is transmitted to the ski other than the skier’s mass."
I agree with your statement which you will see if you read my previous post. I did attempt to delete the post you quoted because I've had enough. You locked me in though
- Verskis
- Posts: 179
- Joined: Fri Oct 27, 2017 2:14 am
- Location: Tampere, Finland
- Ski style: XCD touring on small hills. Heavy tele at resort
- Favorite Skis: Åsnes Rabb 68
- Favorite boots: Alico Ski March
- Occupation: Hydraulics engineer
Re: Physics debate
My education has included quite a lot of physics (Master of science in technology). How about you?GrimSurfer wrote: ↑Tue Jan 03, 2023 12:08 amI have provided quite enough explanation already. I suggest you speak to somebody with a background in physics to explain all this to you. Perhaps they will be able to do so in a way you can more easily understand.
If they manage to get through, feel free to tell your friends.
- Stephen
- Posts: 1487
- Joined: Thu Aug 06, 2020 12:49 am
- Location: PNW USA
- Ski style: Aspirational
- Favorite Skis: Armada Tracer 118 (195), Gamme (210), Ingstad (205), Objective BC (178)
- Favorite boots: Alfa Guard Advance, Scarpa TX Pro
- Occupation: Beyond
6’3” / 191cm — 172# / 78kg, size 47 / 30 mondo
Re: Physics debate
I get the sense that neither side of this “debate” is hearing the other.
The Ski Tip Pressure crowd is saying one thing and GS is saying something different (I think).
GS is saying that the binding is a closed system and isn’t “doing” anything.
It can’t, it has no inherent energy source.
What the Ski Tip Pressure crowd is saying @GrimSurfer, is that the binding does something because of the “activity” introduced by the cable. Of course, you are right in trying to correct the idea of the cable “doing” something, but rather than spend all these pages on trying to prove a point, why not try to figure out why there is no one here intelligent enough to understand what you are saying?
Communication is a circular thing: send, receive, confirm receipt to sender.
There are various goals in communication:
Being right, proving a point, impressing people, seeking self-validation, understanding, etc.
Ultimately, the responsibility for being understood falls on the communicator.
People are either not understanding the fairly simple concepts you, @GrimSurfer present, or they are disagreeing with you.
The only thing I have found to disagree with you about is how a more active binding (whether that is a Meidjo NTN, or a cable binding, or one of many others) can transmit more force to the front of the ski than a less active binding, like a 75mm, with no cable.
However, the Ski Tip Pressure crowd is also failing to get across to GS.
You can blame that on him if you want, but he’s an intelligent guy, and quite capable of understanding. What you want to get across isn’t getting through, partly because of the frustration.
A long time ago, if things had been broken down into bite-size pieces, this would probably all be worked out by now.
@GrimSurfer is trying to present complete ideas, but his large number of words is not helping (this is not a scholarly forum — just a bunch of mostly guys interested in various forms of sliding around on snow).
Fewer words, bite-size chunks.
More asking and less telling might help, too.
I don’t know — I’m starting to sound a little out there.
FWIW…
The Ski Tip Pressure crowd is saying one thing and GS is saying something different (I think).
GS is saying that the binding is a closed system and isn’t “doing” anything.
It can’t, it has no inherent energy source.
What the Ski Tip Pressure crowd is saying @GrimSurfer, is that the binding does something because of the “activity” introduced by the cable. Of course, you are right in trying to correct the idea of the cable “doing” something, but rather than spend all these pages on trying to prove a point, why not try to figure out why there is no one here intelligent enough to understand what you are saying?
Communication is a circular thing: send, receive, confirm receipt to sender.
There are various goals in communication:
Being right, proving a point, impressing people, seeking self-validation, understanding, etc.
Ultimately, the responsibility for being understood falls on the communicator.
People are either not understanding the fairly simple concepts you, @GrimSurfer present, or they are disagreeing with you.
The only thing I have found to disagree with you about is how a more active binding (whether that is a Meidjo NTN, or a cable binding, or one of many others) can transmit more force to the front of the ski than a less active binding, like a 75mm, with no cable.
However, the Ski Tip Pressure crowd is also failing to get across to GS.
You can blame that on him if you want, but he’s an intelligent guy, and quite capable of understanding. What you want to get across isn’t getting through, partly because of the frustration.
A long time ago, if things had been broken down into bite-size pieces, this would probably all be worked out by now.
@GrimSurfer is trying to present complete ideas, but his large number of words is not helping (this is not a scholarly forum — just a bunch of mostly guys interested in various forms of sliding around on snow).
Fewer words, bite-size chunks.
More asking and less telling might help, too.
I don’t know — I’m starting to sound a little out there.
FWIW…