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

--- Quote from: Naej on July 12, 2022, 08:53:28 pm ---
--- Quote from: electrodacus on July 12, 2022, 07:47:12 pm ---
--- Quote from: Naej on July 12, 2022, 07:38:38 pm ---Nah there's plenty of energy available in wind. You know, 1/2*m*v^2 is rarely equal to 0.

--- End quote ---

You get that the air molecules can no longer hit the vehicle when both the vehicle and air molecules have the same speed in the same direction.
Even your wrong wind power equation agrees with that statement.
But since you think over 100% efficiency is possible and think that you get more propulsion power than braking power at the wheels is hard to have a rational discussion.
Until you recognise that above 100% efficiency is not possible. I'm just wasting my time.

--- End quote ---
Do you think a propeller in still air can't work? Lol.
Okay let's wrongly assume there is a problem at this speed. Then when the car goes at twice the wind speed, there's plenty of air for the prop.

Ever heard about heat pumps? They can have 300% efficiency.
If you want to understand why, and how, then you'll have to learn about thermodynamics.

--- End quote ---

??? Where have I said anything about a "propeller in still air" whatever you think that means.
 When vehicle is at 2x the wind speed directly downwind the propeller (part of the vehicle) hits the air molecules not the other way around if you ignore the pressure differential stored energy.
So if you see the air as 1.2kg balls 1m apart traveling at say 10m/s and a vehicle traveling at 20m/s will bump in to the balls slowing down the vehicle not accelerating the vehicle.

A heat pump is what the name implies a pump. It is incorrect to say it is 300% efficient the correct term will be it has a COP (coefficient of performance) of 3.
You have to learn more than just thermodynamics but that will be a good start  so you can stop with the 300% efficiency nonsense.
electrodacus:

--- Quote from: Naej on July 12, 2022, 08:55:08 pm ---The prop is geared to the wheels. If the wheels turn, the prop turns.
And if the prop turns, the kinetic energy of the wind behind the car is reduced, which means you get energy to the car. Very simple.

--- End quote ---

Yes ideal case wheels turn and propeller turns and there is no acceleration as power you put out at the propeller can only be ideal case equal with braking power at the wheels.
But you will not going to get the above as you think above 100% efficiency is possible so until you get that is false we will have a circular conversation.
PlainName:

--- Quote from: electrodacus on July 12, 2022, 08:09:03 pm ---
--- Quote from: dunkemhigh on July 12, 2022, 07:54:31 pm ---
You get that the prop thrust is actually moving backwards from the vehicle, so presenting resistance to the wind which is at vehicle speed?

Ah, forgot, no you don't. In your universe the turning prop doesn't produce thrust of any kind in any direction.

--- End quote ---

You forget that the prop is powered by wind power so if wind power is zero prop power is zero.

--- End quote ---

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?
[/quote]
Naej:

--- Quote from: electrodacus on July 12, 2022, 09:06:06 pm ---
--- Quote from: Naej on July 12, 2022, 08:55:08 pm ---The prop is geared to the wheels. If the wheels turn, the prop turns.
And if the prop turns, the kinetic energy of the wind behind the car is reduced, which means you get energy to the car. Very simple.

--- End quote ---
Yes ideal case wheels turn and propeller turns and there is no acceleration as power you put out at the propeller can only be ideal case equal with braking power at the wheels.
But you will not going to get the above as you think above 100% efficiency is possible so until you get that is false we will have a circular conversation.

--- End quote ---
Ok let's assume that the efficiency, defined as the ratio between the power of the prop and the wind power (1/2*area*density*wind speed^2*car speed), is 50%.
Can you guess the maximal speed?


--- Quote ---the propeller (part of the vehicle) hits the air molecules not the other way around

--- End quote ---
I think before telling people they should learn physics, you should learn relativity. At least the galilean one  ;D
electrodacus:

--- 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 ?
If you say 100W then you are correct so your propeller pushes with 100W and your wheels are braking with 100W so what will be the net of that ?
100W-100W=0W
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