General > General Technical Chat
Force multiplier
pcprogrammer:
--- Quote from: IanB on February 08, 2023, 04:01:38 pm ---The best thing is for us to leave you to your own thoughts and let the thread rest. We do not need to care what you believe, it is not our problem, and it ceases to be entertaining after a while.
--- End quote ---
:-+
And yet, you keep coming back :-DD
Oooh damn now I did too :palm:
electrodacus:
--- Quote from: IanB on February 08, 2023, 04:41:25 pm ---It's not on me at all. You started the thread and are asking the questions. Neither I nor anyone else has any obligation to help you.
--- End quote ---
You seems to be the one making the claim that force multiplication is possible with just two contact points. So it will be on you to demonstrate that.
--- Quote from: IanB on February 08, 2023, 04:41:25 pm ---You can believe whatever you wish. Since everyone else in this thread can make an apparatus that does what the diagrams show it will do, and you alone cannot do so, that is your problem and not our problem.
--- End quote ---
The real device is not doing what the diagram shows. In the diagram there is no slip at any of the wheels while in real world there is slip at one of the wheels else without slip vehicle can not move.
I showed how vehicle can move in the direction of the applied force when output wheel slips and I also showed vehicle moving in the exact opposite direction of the applied force which will normally not be possible but it is due to both energy storage and stick slip hysteresis and witch means none of the two sown cases match your kinematic only prediction.
You can not predict the way a real object moves using only kinematics and ignoring the net force amplitude and direction.
cbutlera:
--- Quote from: electrodacus on February 08, 2023, 03:45:46 pm ---
--- Quote from: cbutlera on February 08, 2023, 11:06:55 am ---...
Try a very simple experiment. Extend the forefingers of you left and right hands, then press the tips of those two fingers together. You will notice that the forces you can feel at your two fingertips are equal and opposite and there is no way of performing this experiment where that would not be the case.
You may regard this experiment as pointless, and that it just demonstrates a law of physics which is intuitive and completely obvious. So obvious in fact that there would be no point in giving it a name. But it does have a name, it is Newton’s third law of motion. A key characteristic of this law is that the two forces involved always act on different objects, in this case the tips of your left and right forefingers.
--- End quote ---
Now you imagine the same experiment but the finger from right hand is under the right wheel and the finger from your left hand is under the left wheel.
Try to bring the hands together and you will understand why it is a locked gearbox and can be treated as a single object.
Your right hand will try to move to the left and you left had to the right and so the right wheel will try to move clockwise and the left wheel counter clockwise.
Due to the way the belt connects the two wheels it will be impossible for the wheels to spin in different directions thus what I call a "locked gearbox"
So unless you allow for one of the wheels to spin on your finger you can not move the hands closer and all you can do is apply a force that will be as you mentioned Newton's 3'rd law of motion.
--- End quote ---
I can think of little further to add to what I wrote in my previous message. You didn't disagree with anything, you just threw in a distraction.
You yourself have claimed to identify the understanding of Newton's third law as the fundamental difference between us. A belt driven trolley is hardly the clearest and simplest example with which to examine that difference.
Here is a definition of Newton's third law that I regard as correct.
"To every action, there is always opposed an equal reaction; or, the mutual actions of two bodies upon each other are always equal, and directed to contrary parts."
The left wheel of your trolley is a different object to the right wheel, the stationary block and the treadmill belt are also different objects. So your F1 and F2 cannot be viewed as the mutual actions of two bodies upon each other, and are therefore not the subject of Newton's third law as defined above.
If you have a definition of Newton's third law that makes your F1 and F2 a Newton's third law force pair, then please write it down.
electrodacus:
--- Quote from: cbutlera on February 08, 2023, 06:08:32 pm ---I can think of little further to add to what I wrote in my previous message. You didn't disagree with anything, you just threw in a distraction.
You yourself have claimed to identify the understanding of Newton's third law as the fundamental difference between us. A belt driven trolley is hardly the clearest and simplest example with which to examine that difference.
Here is a definition of Newton's third law that I regard as correct.
"To every action, there is always opposed an equal reaction; or, the mutual actions of two bodies upon each other are always equal, and directed to contrary parts."
The left wheel of your trolley is a different object to the right wheel, the stationary block and the treadmill belt are also different objects. So your F1 and F2 cannot be viewed as the mutual actions of two bodies upon each other, and are therefore not the subject of Newton's third law as defined above.
If you have a definition of Newton's third law that makes your F1 and F2 a Newton's third law force pair, then please write it down.
--- End quote ---
While you may consider the left wheel a different object from the right wheel in this particular example they are not.
The way let and right wheel are connected to each other makes them act as a single object.
This equivalent diagram to (a) may make it more visible to you
You can als imagine having this in your hands right hand applies F1 and the left hand will apply the equal and opposite force F2 else there will be no F1 so Newton's 3'rd law pair.
All this pairs in the above diagram are newton's 3'rd law pairs so F1 = F2, F3 = F4 and F5 = F6
IanB:
--- Quote from: electrodacus on February 08, 2023, 06:28:48 pm ---You can als imagine having this in your hands right hand applies F1 and the left hand will apply the equal and opposite force F2 else there will be no F1 so Newton's 3'rd law pair.
--- End quote ---
Once again you are assuming something that isn't true. If you hold that object in your hands and try to apply opposing forces F1 and F2 then the object will simply move and rearrange itself to cancel out the forces, so that no force remains. It will be like trying to apply a force to an object that moves out of the way when you touch it. In reality there are no forces on that system, all forces are zero.
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