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| IanB:
--- Quote from: fourfathom on December 21, 2021, 02:53:36 am ---Speaking an an electronics nerd who skipped Physics, I think of power in Watts. Watts = Volts * Amps, and there is no time dimension unless you consider that Amps = Coloumbs per second. But that is a rate, not a duration. Even Watt-hours is rate, or a quantity, with no particular duration (unless specified). I look forward to some clarification. --- End quote --- The SI system is a bit sneaky, as it defines fundamental dimensions (among others) as length (L), mass (M), time (T) and electric current (I). But electric current implicitly contains time, as it is charge/time. So dimensions containing current will contain a hidden time dimension. Now voltage has dimensions of (work)/(charge), where work is dimensionally equivalent to energy, and current is (charge)/(time). So power = voltage x current, and has dimensions of (work)/(charge) x (charge)/(time) = (work)/(time). Now (work)/(time) is "the rate of doing work", which is the conventional definition of power, so it all lines up. |
| electrodacus:
--- Quote from: Brumby on December 21, 2021, 12:20:07 am ---You seemed to have "overlooked" this: --- Quote from: Brumby on December 20, 2021, 07:51:33 am --- --- Quote from: electrodacus on December 19, 2021, 05:45:16 am ---Do you understand that power you take from the wheel will brake the vehicle ? --- End quote --- --- Quote from: electrodacus on December 19, 2021, 05:53:12 pm ---If you talk about power and taking a power from the wheel then there is no speed change as power is instantaneous contains no time dimension. --- End quote --- Which is it? You can't have it both ways. --- End quote --- Care to answer? --- End quote --- Yes I was talking for the vehicle reference frame and in that case vehicle will not move but you need to consider the 10W in that example braking power. So no matter how you look at things taking power from generator wheel means deceleration and while in vehicle reference frame and while you use just power no specification for time duration you get Net power that will be the output at motor wheel minus the input at the generator wheel. If that net power is negative while is just a value it means vehicle will decelerate. I'm fairly bad at explaining but when you use power there is no time involved so you get a net power that can be positive meaning vehicle can accelerate or negative meaning vehicle will decelerate when you add the time step. |
| Brumby:
--- Quote from: electrodacus on December 21, 2021, 03:27:36 am ---I'm fairly bad at explaining --- End quote --- No kidding. You are even worse at understanding. Your entire response completely overlooks the point I was making - and the focus on power and time just shows you are just babbling on, trying to make your argument sound "scientific", but is way short of the mark. --- Quote from: fourfathom on December 21, 2021, 02:53:36 am ---But honestly, trying to fine-tune and correct these equations is fairly pointless when they do not reflect the actual characteristics of these DDWFTTW vehicles any system. --- End quote --- Precisely this. |
| electrodacus:
--- Quote from: bdunham7 on December 21, 2021, 12:29:44 am --- --- Quote from: electrodacus on December 19, 2021, 05:53:12 pm ---power is instantaneous contains no time dimension. --- End quote --- It doesn't? Power = Energy/Time. Joules per second. Ergs per eon. Electron-volts per attosecond. --- End quote --- Power contains no time component just the energy contains time. Power is measured in Watt while energy is measured in Joules same as Watt second If I say a power of 10W is applied for 1ms then you have the energy as 10mJ = 10mWs = 0.01Ws So yes Power = Energy/Time but the part containing time is Energy not Power that is why you divide by time to get the power. So in this example 10W = 0.01Ws / 0.001s |
| bdunham7:
--- Quote from: electrodacus on December 21, 2021, 03:35:58 am ---Power contains no time component just the energy contains time. Power is measured in Watt while energy is measured in Joules same as Watt second So yes Power = Energy/Time but the part containing time is Energy not Power that is why you divide by time to get the power. --- End quote --- That's some extraordinarily convoluted babbling, even for you. Power literally has no definition other than energy per unit time, or rate of energy transfer. An amount of energy can be stored (as potential energy, like a compressed spring) for an arbitrary amount of time. |
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