| From: llama | 12/07/00
0:00:49 |
| Subject: perpetual motion | post id:
97482 |
| If you connected a petrol motor
to a generator with an electrical motor driven by the power of the
generator would this not be perpetual motion?? And could another electrical motor be driven of this power also?? | |
| From: Terry Frankcombe (Avatar) | 12/07/00
0:05:07 |
| Subject: re: perpetual motion | post id:
97483 |
| If you connected
a petrol motor to a generator with an electrical motor driven by the power
of the generator would this not be perpetual motion?? And could another
electrical motor be driven of this power also?? No, and yes. It's perpetual motion as long as you keep up petrol to the motor! 'Fraid this don't count! Running electric motors off generators running off diesel motors is how diesel-electric trains work. | |
| From: llama | 12/07/00
0:19:17 |
| Subject: re: perpetual motion | post id:
97484 |
| If the petrol motor was turn of
after it had generated electricty via the electric motor the petrol motor
would be redundant | |
| From: Chris W (Avatar) | 12/07/00
0:35:35 |
| Subject: re: perpetual motion | post id:
97485 |
| OK, so you're talking about the
electric motor driving the generator that powers it. Let's look at it logically then. Start with idealised devices with perfect performance. The maximum possible electrical output from the generator is equal to the mechanical energy input. The maximum possible mechanical output from the motor is equal to the electrical power input. So, if you connected these devices in the manner you describe (using perfect wiring of course) and provide an initial spin of the generator they'd run forever. Now, let's use the real world. No generator converts mechanical energy to electrical energy with 100% efficiency. Energy is lost overcoming friction in bearings, air resistance spinning the rotor, magnetic back force caused by current induced in the generator coils, heat loss and probably some others. The electricity is transmitted to the motor through imperfect wires that suffer losses through heating. The motor converts electrical energy to mechanical with less than 100% percent efficiency for the same reasons the generator is imperfect. The motor will be coupled to the generator through some gearbox arrangment that loses energy to friction and vibration. After one cycle you have less mechanical energy than you put in; the spiral is downward to nothing. If you were drawing current to drive a second motor then you are further depleting the mechanical energy available to drive the generator. So, the answer to the question is No. | |