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Electroboom: How Right IS Veritasium?! Don't Electrons Push Each Other??

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Naej:

--- Quote from: electrodacus on July 12, 2022, 09:46:18 pm ---
--- Quote from: Naej on July 12, 2022, 09:36:58 pm ---No a propeller gives thrust, unless the blade angle is incorrect.
If you insist with -1000W, with an output of 400W you'll have an efficiency of -40%.
It's pretty silly, but if you are amused by it, why not.

--- End quote ---

Do you have a problem considering the vehicle powered by 1.2kg balls spaced 1m apart ? say balls travel at 10m/s
You are in your vehicle no matter the design as long as you have no energy source on board and you will not use your mussels to power the vehicle.
Do you think this ball powered vehicle you find yourself in can exceed the speed of the balls ?

-when you are stationary you get the most power as 10 balls will hit your vehicle very second.
-when vehicle is at 5m/s only 5 balls will hit the vehicle very second and relative to vehicle the balls will only be at 5m/s so less balls hitting the vehicle softer.
-when vehicle is at 10m/s (say no friction and you got there) no balls can hit your vehicle so no ball power.
But say someone pushes you to 20m/s
-will your vehicle not hit now 10 balls each second at 10m/s so your vehicle will be slowed down?

If you think a non compressible fluid is different from this balls explain how.

--- End quote ---
You are correct in that with a sail you can't go faster than the wind.
The solution here is to use gears with the wheels to a bat, and the bat hits the balls and accelerate them by 10m/s for example.
So before the car they have 1/2*m*10²  in kinetic energy and after they have 0. Can you guess where the kinetic energy went?

PlainName:

--- Quote from: electrodacus on July 12, 2022, 09:15:12 pm ---
--- Quote from: dunkemhigh on July 12, 2022, 09:11:06 pm ---What part of "turning prop" don't you understand? It doesn't matter where the power comes from, if the prop is turning it's producing thrust. And in EVERY demo we've seen, the prop is turning. It is thus producing thrust.

Are you denying that?

--- End quote ---

Say propeller produces 100W of thrust.
How much power do wheels need to deliver to an ideal propeller for that 100W worth of thrust ?

--- End quote ---

Completely irrelevant. Either it is producing thrust - small, large, whatever - or it is not. You can argue about how much and where the power is coming from later.

So, are you saying a turning prop is not producing thrust?

electrodacus:

--- Quote from: Naej on July 12, 2022, 09:49:50 pm ---
You are correct in that with a sail you can't go faster than the wind.
The solution here is to use gears with the wheels to a bat, and the bat hits the balls and accelerate them by 10m/s for example.
So before the car they have 1/2*m*10²  in kinetic energy and after they have 0. Can you guess where the kinetic energy went?

--- End quote ---

You can go faster than wind with a sail vehicle if you add energy storage so take energy from the wheel store in a battery or flywheel and use that to exceed wind speed.
The amount you gain by hitting the ball will be using at the wheel to brake the vehicle so you gain nothing.
The problem is you thinking you can get more from the bat compared to what you stole at the wheel but that is never the case in this universe.

If your vehicle is at 20m/s and vehicle mass is say 300kg then vehicle kinetic energy is 0.5 * 300 * 202 = 60000Ws
Now you apply say a brake of 10N for a fraction of a second say 0.001s that will get you 100N * 20m/s * 0.001s = 2Ws
So the vehicle is now at just 59998Ws (lower speed)
And you take this 2Ws you got from the wheels and put it in a 100% efficient bat then what will happen is you best case put those stollen 2Ws back and you are now back from where you started at 60000Ws so same speed as it is the ideal case.
Do you understand how useless it will be to have a bat connected to wheels when vehicle is powered by balls ?

electrodacus:

--- Quote from: dunkemhigh on July 12, 2022, 10:09:58 pm ---
Completely irrelevant. Either it is producing thrust - small, large, whatever - or it is not. You can argue about how much and where the power is coming from later.

So, are you saying a turning prop is not producing thrust?

--- End quote ---

Actually highly relevant.
The propeller produces thrust but the energy it took from the wheels produced what you can call anti-thrust.
As when you take energy at the wheel you apply brakes to vehicle.

The only reason this even makes any sense (having propeller conned to wheels) is because it can be used as an energy storage device due to air being a compressible fluid.
So when vehicle starts it may be more like 100W taken at the wheels and propeller 70% efficient  60W go to storage 10W is thrust and 30W lost as heat due to propeller and gear inefficiency.
That accumulated stored energy over time will take over the propulsion and allow vehicle to get well above wind speed for some limited amount of time.

Naej:

--- Quote from: electrodacus on July 12, 2022, 10:11:22 pm ---And you take this 2Ws you got from the wheels and put it in a 100% efficient bat then what will happen is you best case put those stollen 2Ws back and you are now back from where you started at 3000Ws so same speed as it is the ideal case.
Do you understand how useless it will be to have a bat connected to wheels when vehicle is powered by balls ?

--- End quote ---
You forgot about the balls and their energy.  :-DD

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