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Mess with your minds: A wind powered craft going faster than a tail wind speed.

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electrodacus:

--- Quote from: IanB on September 03, 2021, 05:21:25 pm ---
--- Quote from: electrodacus on September 03, 2021, 05:12:42 pm ---The Power equation is hard to mess up
--- End quote ---

Apparently it is really easy to mess up, as you keep doing so with your treadmill example and the nonsense conclusion that the cart cannot move from left to right when powered by the treadmill.

It is clear that if the G wheel can pick up power then the M wheel can receive power. If the M wheel can receive power, then it can equally well be made to turn clockwise or anti-clockwise (it just depends on the gearing). If the M wheel turns clockwise the cart will move from left to right.

There is nothing at all preventing the M wheel from turning clockwise. If it receives power, it can turn.

--- End quote ---

Please provide the correct power equation so I can see where I did the mistake.
To get any energy from G wheel the vehicle will need to move backwards (right to left) and putting that generated energy back in to M wheel will be enough in ideal case to bring the vehicle back to original position thus not possible for vehicle to move from left to right.

cbutlera:

--- Quote from: electrodacus on September 03, 2021, 05:12:42 pm ---
--- Quote from: cbutlera on September 03, 2021, 04:26:08 pm ---Are there any of Newton's laws that you agree with?

--- End quote ---

So now you can look at speeds and say wheel speed is 5m/s it means breaking force was 2N
And if say the other medium you pushed against only had 2.5m/s you will have needed 4N to be able to push with 10W for 1 second and get the vehicle kinetic energy back to where it was.
You see the 4N is higher than 2N and you think vehicle will gain speed but that is not the case and in ideal case the vehicle will just be able to maintain speed.
The problem is you are confusing the force at the wheel with forces acting against the vehicle.

--- End quote ---

Thanks, I'll take that as a no.

electrodacus:

--- Quote from: cbutlera on September 03, 2021, 05:38:02 pm ---
Thanks, I'll take that as a no.

--- End quote ---

You did not read my answer if that is your conclusion. Newton laws are correct you just do not know how to apply them when vehicle acts against two separate mediums.

bdunham7:

--- Quote from: electrodacus on September 03, 2021, 05:22:59 pm ---Wall is fixed to the ground so that energy is transferred to earth. When vehicle accelerated it has pushed against earth accelerating the earth in opposite direction then when vehicle hit the wall all that energy was put back in to earth in opposite direction to initial acceleration.
Vehicle had 9Ws of kinetic energy before hitting the wall and 0Ws after. So where do you think that 9Ws disappeared ?

--- End quote ---

Nope!  If you do the math properly, you'll find that the energy transferred to that much larger system is absolutely miniscule.  This is a variant on a standard high-school level physics question that is often initially answered wrongly because the wrong law (conservation of energy) is applied when the correct result is obtained by using the law (conservation of momentum).  So yes, the 9Ws 'disappears', why don't you figure out where it goes.  Or, reflect on the fact that you apparently don't know where it goes.  It's a very basic question.


--- Quote ---You seems to be the one not understanding that force at the wheel (or propeller) is not the same with force against the body of the vehicle.
Think about a gearbox only that is 2:1 ideal so no friction.
I'm on the input side putting 1N and you are at the output side and will need to put 2N so that gearbox is in equilibrium no movement.
have you got the equilibrium part ? There is a huge difference in forces but no movement in any direction.

--- End quote ---

Since you said gearbox, I'll assume you mean newton-meter (torque).  Or you could use a lever example if you like.  In any case, the only reason you imagine that works is because you do not understand the laws of motion.

For every action there is an equal and opposite reaction.   And 'action' means force.

Now for your gearbox example, indeed the lever-action of the gears will result in no movement, provided the gearbox body is held in place.  Whatever is holding it in place will have to provide 1N/m of torque as a reaction, otherwise the body of the gearbox will just rotate.  If you see an example of unequal forces but no movement, it is because you have not properly accounted for all of the forces.

bdunham7:

--- Quote from: electrodacus on September 03, 2021, 05:43:41 pm ---You did not read my answer if that is your conclusion. Newton laws are correct you just do not know how to apply them when vehicle acts against two separate mediums.

--- End quote ---

F = ma.

That's the whole thing.  Explain how 'different mediums' is accounted for in that law or 'how you apply it'.  F means force, m means mass, a means acceleration.  There's no mysterious correction factor for 'separate mediums' or anything else.

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