How do I explain perpetual motion to my 8 years old sister?
The other day I kind of went too far on physic matters with my 8 years old sister and go into perpetual motion. I said that perpetual motion machines can't exist because it would violate the 1st and 3rd law of thermodynamics.
Why not? She asked.
Then I figure out that even I don't really understand all the 100% energy efficient thing. I know that you need energy to fight air resistance and friction, but why can't perpetual machines exist? And how do I explain it to my sis?
Thanks a tank! :D:D:D:D:D:D