News for hackers. Stuff that matters.

A comment on The swimming of a dead fish (2018). Parent comment

Re:The swimming of a dead fish (2018) by hankh18 on Wednesday April 20, 2022 @01:23PM (#31100158)
Well even without the fish moving itself it wouldn't be a perpetual motion machine because the running water would be an input to the system. Agree though that a living, untethered fish would need to expend energy to stay balanced and in the right spot.
[ Parent | on HN ]
Re:The swimming of a dead fish (2018) by JoeAltmaier on Wednesday April 20, 2022 @02:26PM (#31100992)
Reframe the system to the moving water. The fish is then swimming upstream.

All frames of reference are valid. So yes, perpetual motion.

[ Parent | on HN ]
Re:The swimming of a dead fish (2018) by PeterisP on Wednesday April 20, 2022 @10:06PM (#31105331)
Reframe the system to the moving water and put a watermill or a hydroelectric power plant in there in there - perpetual motion and extracting energy. A flowing river is not a closed system.
[ Parent | on HN ]
Re:The swimming of a dead fish (2018) by plutonorm on Wednesday April 20, 2022 @06:06PM (#31103686)
what about sailing up wind?
[ Parent | on HN ]