General > General Technical Chat
Force multiplier
electrodacus:
--- Quote from: IanB on February 12, 2023, 10:31:30 pm ---But it doesn't show that, does it?
By saying this, you are only showing you are not able to read or understand the analysis provided by Nominal Animal, and if you are not able to read or comprehend such an analysis, you are not able or qualified to make any claims about anything under discussion.
This is why everyone thinks you are either a troll or a fool.
Under such circumstances there is no point trying to debate anything you say.
--- End quote ---
If you remember his kinematic only model treadmill moved the ground moved and vehicle moved. So set a 1:1 gear ratio in that model and you can show treadmill and ground moving same distance in same direction while vehicle remains in the same place and of course wheels rotate.
That is because the kinematic model does not care about forces and where they are applied.
Nothing ever in this universe as far as we know moves directly against the direction of applied force without using energy storage. Where will the net force come from if you can not have force multiplication ? Or did you found the proof that you can do force multiplication with just two points of contact.
In vehicle (a) F2 is only larger when F3 and F4 change direction (discharging energy stored in the belt) so in that moment vehicle is no longer powered by treadmill but by belt stored energy and due to offset of those applied forces F2 > F1 for that sort period of time during discharge.
But what I I build a higher quality vehicle get a high frame rate camera and I show you with say a 3:1 or 4:1 that front wheel slips intermittently while vehicle looks to drive smoothly at real time video but intermittent slip when video is slowed down. Will such a video convince you that energy storage is used ?
electrodacus:
--- Quote from: PlainName on February 12, 2023, 11:58:53 pm ---
For the purpose of the actual problem, why does it need to be a 'perfectly continues motion'? So long as overall it is in the right direction surely that's all that counts.
--- End quote ---
Not it is not all that counts.
All that counts is the description of what happens. Correct theory so you can make accurate prediction.
If you use the wrong theory to make predictions and the result seems almost correct will you consider that to be fine ?
PlainName:
--- Quote ---All that counts is the description of what happens. Correct theory so you can make accurate prediction.
--- End quote ---
Sounds good. When are you going to try that?
electrodacus:
--- Quote from: PlainName on February 13, 2023, 12:32:11 am ---
--- Quote ---All that counts is the description of what happens. Correct theory so you can make accurate prediction.
--- End quote ---
Sounds good. When are you going to try that?
--- End quote ---
I already did that multiple times but here is the description.
Configuration (a) is locked so it can not move unless applied force is large enough for the wheel to slip on the surface it is in contact with.
I had a super lightweight plastic vehicle with some hard rubber wheels on paper thus nut much force is needed for the wheels to slip.
This can be measured if you are not convinced.
Before it slips some energy is stored if there is a force and the treadmill surface moved.
Potential elastic energy = Force * distance the treadmill moved before wheel slip.
The moment wheel slips force at the input wheel drops significantly allowing part of potential elastic energy to be converted to potential kinetic energy.
The belt will no longer be stretched as the wheel slips and so F3 and F4 change direction and pull on the two different size pulleys so F2 larger for a brief moment as the potential elastic energy is converted to potential kinetic energy.
At this point the input wheel sticks again and the cycle repeats.
PlainName:
--- Quote from: electrodacus on February 13, 2023, 12:59:06 am ---
--- Quote from: PlainName on February 13, 2023, 12:32:11 am ---
--- Quote ---All that counts is the description of what happens. Correct theory so you can make accurate prediction.
--- End quote ---
Sounds good. When are you going to try that?
--- End quote ---
I already did that multiple times but here is the description.
--- End quote ---
You already made the prediction but the reality doesn't agree. Even your model, complete with your fantasy stick/slip, overall moves in the 'wrong' direction. And that's your prediction with 20/20 hindsight! Hope you're not involved with TV weather forecasts.
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