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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 09, 2022, 09:35:24 pm ---
--- Quote ---The amount of power available to a wind powered vehicle (any design) is 1/2*mass flow*wind speed^2. If the vehicle seed is twice the wind speed, you get mass flow=density*area*wind speed.

--- End quote ---

We are making progress as now you say that wind power available to vehicle is the same as I always say but just with the equation presented a bit different

You wrote:
0.5 * (air density * area * wind speed) * wind speed2

That is correct and the same with
0.5 * air density * area * wind speed3

All you need to clarify now is that wind speed in this equation is wind speed relative to vehicle and not to the ground.
The wind speed relative to vehicle = (wind speed relative to ground - vehicle speed relative to ground) and now you will have the equation I provided you with many times.

--- End quote ---
I didn't write this. You did.
I'm glad you agree with my correct formula (yours is not).
I can clarify: wind speed is relative to ground.


--- Quote from: electrodacus on July 09, 2022, 09:35:24 pm ---Now when vehicle is at 2x the wind speed you have

0.5 * air density * area * (wind speed - (2 * wind speed))3  = 0.5 * air density * area * (-wind speed)3

Notice the negative sign in front of wind speed meaning negative power relative to vehicle meaning vehicle will be slowed down / decelerated at that rate and not accelerated.
The vehicle hits the air not the air hits the vehicle when vehicle speed is 2x wind speed.

If you replace air (compressible fluid) with water (incompressible fluid) you can no longer store energy in pressure differential thus you can no longer demonstrate 2x or 3x fluid flow speed for that vehicle.

--- End quote ---
Notice how there's no minus sign in my formula (the correct one).
Also you didn't compute the dam speed.

electrodacus:

--- Quote from: Naej on July 09, 2022, 11:48:53 pm ---I didn't write this. You did.
I'm glad you agree with my correct formula (yours is not).
I can clarify: wind speed is relative to ground.

--- End quote ---

You did wrote exactly that.
Wind speed in your equation is not relative to the ground.

Just think about a 1.2kg ball traveling at say 10m/s relative to ground hitting a stationary vehicle (vehicle zero speed relative to ground)
Then imagine same ball with same 10m/s relative to ground hitting a vehicle that drives at 9m/s relative to ground in the same direction.
The speed of the ball relative to vehicle is just 1m/s (10m/s-9m/s) and so it will transfer way less energy to vehicle.
Then imagine the vehicle at say 15m/s relative to ground in same direction as the ball that travels at just 10m/s and in this case what happens is that vehicle will hit the ball at 5m/s so vehicle will be slowed down by this interaction.



--- Quote from: Naej on July 09, 2022, 11:48:53 pm ---Notice how there's no minus sign in my formula (the correct one).
Also you didn't compute the dam speed.

--- End quote ---

Look closer. I considered your example where vehicle speed is 2 * wind speed and it is correctly applied in the equation as wind speed relative to vehicle is minus wind speed since vehicle will see a head wind.
Maybe the ball example above is more clear.

Naej:

--- Quote from: electrodacus on July 10, 2022, 12:02:49 am ---
--- Quote from: Naej on July 09, 2022, 11:48:53 pm ---I didn't write this. You did.
I'm glad you agree with my correct formula (yours is not).
I can clarify: wind speed is relative to ground.

--- End quote ---

You did wrote exactly that.
Wind speed in your equation is not relative to the ground.

--- End quote ---
No. Don't tell me what I meant.
The amount of power available to a wind powered vehicle (any design) is 1/2*mass flow*wind speed². If the vehicle seed is twice the wind speed, you get mass flow=density*area*wind speed.



--- Quote from: electrodacus on July 10, 2022, 12:02:49 am ---Just think about a 1.2kg ball traveling at say 10m/s relative to ground hitting a stationary vehicle (vehicle zero speed relative to ground)
Then imagine same ball with same 10m/s relative to ground hitting a vehicle that drives at 9m/s relative to ground in the same direction.
The speed of the ball relative to vehicle is just 1m/s (10m/s-9m/s) and so it will transfer way less energy to vehicle.
Then imagine the vehicle at say 15m/s relative to ground in same direction as the ball that travels at just 10m/s and in this case what happens is that vehicle will hit the ball at 5m/s so vehicle will be slowed down by this interaction.

--- End quote ---
No. Let's say a guy in the vehicle slaps the ball at 10 m/s. Then the ball lost its kinetic energy, and the car is propelled.

--- Quote from: electrodacus on July 10, 2022, 12:02:49 am ---
--- Quote from: Naej on July 09, 2022, 11:48:53 pm ---Notice how there's no minus sign in my formula (the correct one).
Also you didn't compute the dam speed.

--- End quote ---

Look closer. I considered your example where vehicle speed is 2 * wind speed and it is correctly applied in the equation as wind speed relative to vehicle is minus wind speed since vehicle will see a head wind.
Maybe the ball example above is more clear.

--- End quote ---
Look closer, there is no minus sign: The amount of power available to a wind powered vehicle (any design) is 1/2*mass flow*wind speed². If the vehicle seed is twice the wind speed, you get mass flow=density*area*wind speed.

electrodacus:

--- Quote from: Naej on July 10, 2022, 12:19:58 am ---No. Don't tell me what I meant.
The amount of power available to a wind powered vehicle (any design) is 1/2*mass flow*wind speed². If the vehicle seed is twice the wind speed, you get mass flow=density*area*wind speed.

Look closer, there is no minus sign: The amount of power available to a wind powered vehicle (any design) is 1/2*mass flow*wind speed². If the vehicle seed is twice the wind speed, you get mass flow=density*area*wind speed.

--- End quote ---

So what you are saying is that vehicle speed is nowhere in your equation meaning non important ?
If you are not saying that then show where the vehicle speed fits.


--- Quote from: Naej on July 10, 2022, 12:19:58 am ---No. Let's say a guy in the vehicle slaps the ball at 10 m/s. Then the ball lost its kinetic energy, and the car is propelled.

--- End quote ---

Yes but what powers the guy ? And is the ball stationary relative to the guy ?
If ball moves relative to the guy then amount of kinetic energy it will gain will be very different depending on both speed and direction.

Naej:

--- Quote from: electrodacus on July 10, 2022, 12:31:01 am ---
--- Quote from: Naej on July 10, 2022, 12:19:58 am ---No. Don't tell me what I meant.
The amount of power available to a wind powered vehicle (any design) is 1/2*mass flow*wind speed². If the vehicle seed is twice the wind speed, you get mass flow=density*area*wind speed.

Look closer, there is no minus sign: The amount of power available to a wind powered vehicle (any design) is 1/2*mass flow*wind speed². If the vehicle seed is twice the wind speed, you get mass flow=density*area*wind speed.

--- End quote ---

So what you are saying is that vehicle speed is nowhere in your equation meaning non important ?
If you are not saying that then show where the vehicle speed fits.

--- End quote ---
I'm not.
Mass flow is close to the density*area*relative wind speed.
(Not equal because when you have a relative wind speed equal to 0, you can still get some mass flow on your propeller)

--- Quote from: electrodacus on July 10, 2022, 12:31:01 am ---
--- Quote from: Naej on July 10, 2022, 12:19:58 am ---No. Let's say a guy in the vehicle slaps the ball at 10 m/s. Then the ball lost its kinetic energy, and the car is propelled.

--- End quote ---

Yes but what powers the guy ? And is the ball stationary relative to the guy ?
If ball moves relative to the guy then amount of kinetic energy it will gain will be very different depending on both speed and direction.

--- End quote ---
The wheel. Perhaps the guy is some gears connected to the wheel.
And the ball stops moving relative to the ground, it loses its kinetic energy.

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