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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, 09:15:12 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 ? 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 --- End quote --- I say 30W coming from the gear and 1000W from the wind, at twice the wind speed. |
| electrodacus:
--- Quote from: Naej on July 12, 2022, 09:14:21 pm --- 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? --- End quote --- Efficiency will not be defined as those two quantities. Input is wind power and nothing else. Output = Input - friction losses. Ideal case you have no friction loss and so 100% of input power is converted into kinetic energy. |
| electrodacus:
--- Quote from: Naej on July 12, 2022, 09:21:53 pm --- I say 30W coming from the gear and 1000W from the wind, at twice the wind speed. --- End quote --- If vehicle is at 2x the wind speed directly downwind you will refer to that wind power as -1000W (yes negative) meaning it will slow down the vehicle. As input there can not be anything else other than wind power and what you fail to accept power from stored energy |
| Naej:
--- Quote from: electrodacus on July 12, 2022, 09:30:38 pm --- --- Quote from: Naej on July 12, 2022, 09:21:53 pm --- I say 30W coming from the gear and 1000W from the wind, at twice the wind speed. --- End quote --- If vehicle is at 2x the wind speed directly downwind you will refer to that wind power as -1000W (yes negative) meaning it will slow down the vehicle. As input there can not be anything else other than wind power and what you fail to accept power from stored energy --- End quote --- 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. |
| electrodacus:
--- 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. |
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