# Homework Help: Perpetual motion

1. Jul 15, 2004

### dajugganaut

Question:

A student once came up with an idea for a perpetual motion machine. His idea was as follows: Point an electric fan at a wind generator. Blow on the blades of the wind generator to activate it. As the generator produces electricity, it is used to ppower the electric gan which in turn keeps the generator going which in turn keeps the fan going...etc. Once set in motion, it would keep going forever until you stopped it.

would this work? please explain why or why not
(well of couse not, but please explain)

2. Jul 15, 2004

### Zurtex

Consider, is there any system that is 100% efficent?

3. Jul 15, 2004

### dajugganaut

well obviously not, but what exactly is the flaw in this perpetual motion that would make it not work??

4. Jul 15, 2004

### Zurtex

Well I can think of many many flaws in that system. Try and think where energy would be lost.

5. Jul 15, 2004

### dajugganaut

friction for both the fan and the wind generator, but i cannot see exactly /how/ its lost

6. Jul 15, 2004

### Zurtex

Well friction turns the kenetic energy in the system to heat. Is that heat then used in the system or just wasted?

Also would the wind travel the whole distance and be 100% effective?

Think also abour the resistance in the wires.

7. Jul 15, 2004

### dajugganaut

ok, i see your point zurtex, thanks!