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Force multiplier
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IanB:
In the ideal world of diagram (a) there are no forces, therefore no analysis based on force balances or force pairs can exist.

To put this plainly, F1, F2, F3 and F4 are always, unavoidably, and exactly zero. It is not possible to make them anything other than zero.

Force balance analysis can only be applied to static systems (the branch of applied mathematics called "statics"). In picture (a) the wheeled assembly is moving freely from left to right and there is no resistance to motion for forces to exist.*

The physical simile is a free body moving in space at constant velocity, being pushed by a force labeled "F". It is clear that F must be zero, since a body moving at constant velocity in free space experiences no forces.

* Unless we introduce factors like friction in bearings.
cbutlera:

--- Quote from: electrodacus on February 07, 2023, 01:06:21 am ---
--- Quote from: cbutlera on February 07, 2023, 12:39:20 am ---
But F1 and F2 are not a Newton’s third law force pair.  Carefully read again the paragraph from page 5 of the paper regarding the N2-NF misconception.  It addresses precisely this issue.  Have you now decided that you do not agree with the arguments presented in this paper?


--- End quote ---

What will you say that F1 = F2 are a consequence of if not Netwonds 3'rd law ?
Or are you saying F1 is not equal with F2 in my examples ?

If so please explain how F1 can be different from F2. What is the mechanism to allow that ?

--- End quote ---

Yes, F1 is not equal and opposite to F2 in your examples, except in the case where both are zero.

The vehicle in example a) and the cylinder in example b) both have an internal mechanism that guarantees that F1 and F2 will have different magnitudes (except in the case where both are zero).  This should be most obvious in example b).  Both pistons are exposed to the same fluid pressure, but they have different working surface areas, so as a consequence, F1 and F2 will have different magnitudes.

Sorry, it’s getting very late.  I need to sign off now.
electrodacus:

--- Quote from: IanB on February 07, 2023, 01:33:05 am ---In the ideal world of diagram (a) there are no forces, therefore no analysis based on force balances or force pairs can exist.

To put this plainly, F1, F2, F3 and F4 are always, unavoidably, and exactly zero. It is not possible to make them anything other than zero.

Force balance analysis can only be applied to static systems (the branch of applied mathematics called "statics"). In picture (a) the wheeled assembly is moving freely from left to right and there is no resistance to motion for forces to exist.*

The physical simile is a free body moving in space at constant velocity, being pushed by a force labeled "F". It is clear that F must be zero, since a body moving at constant velocity in free space experiences no forces.

* Unless we introduce factors like friction in bearings.

--- End quote ---

Why do you say in diagram a there can be no forces in ideal case ?
So you saying that appling F1 the assembly will just move freely in the opposite direction of applied force ? How will that ever make sense ?

What about case b) as that is simpler to visualize ?  Will there be possible to apply a force F1 ? and will F2 not be equal and opposite to F1?
electrodacus:

--- Quote from: cbutlera on February 07, 2023, 01:43:02 am ---Yes, F1 is not equal and opposite to F2 in your examples, except in the case where both are zero.

The vehicle in example a) and the cylinder in example b) both have an internal mechanism that guarantees that F1 and F2 will have different magnitudes (except in the case where both are zero).  This should be most obvious in example b).  Both pistons are exposed to the same fluid pressure, but they have different working surface areas, so as a consequence, F1 and F2 will have different magnitudes.

Sorry, it’s getting very late.  I need to sign off now.

--- End quote ---

As I suspected you have the same misunderstanding as the other about the mechanisms in the 3 examples.
I already shown in video that F1 = F2 and also significantly large (can be calculated by the amount the belt was stretched).

The internal mechanism in a) and b) can not do force amplification / multiplication in the way they are set up.
For that to be true the body of the vehicle in a) (blue part) will need to be connected rigidly to ground and same in case b) the cylinder will need to be connected to ground.
Yes fluid pressure is the same also F2 equal and opposite to F1.  Please do a google search for a torque multiplier and see if that works with just two points of contact as in my examples a) and b).   You will find out that all torque multipliers requires 3 points of contact in order to work. 
IanB:

--- Quote from: electrodacus on February 07, 2023, 01:45:29 am ---Why do you say in diagram a there can be no forces in ideal case ?
--- End quote ---

It's a diagram, so there are no frictional forces and no inertial forces. There are also no rigid bodies. Therefore no forces.


--- Quote ---So you saying that appling F1 the assembly will just move freely in the opposite direction of applied force ? How will that ever make sense ?
--- End quote ---

You cannot apply F1 because there are no forces. If the belt is turning as in the picture then the wheels will be turning clockwise and the assembly will be moving to the right. No forces are required for this to be happening.


--- Quote ---What about case b) as that is simpler to visualize ?  Will there be possible to apply a force F1 ? and will F2 not be equal and opposite to F1?
--- End quote ---

There is no need to discuss case (b) as that is different and therefore not relevant.
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