[Phys-L] Counter-intuit
I expect you have seen a model demonstrate sailing directly upwind? It
comprises an airscrew driving a car whell or a water screw.
https://www.google.com/search?q=youtube+DTU+wind+turbine+racer&rlz=1C1CHBD_enUS945US945&oq=youtube+DTU+wind+turbine+racer&gs_lcrp=EgZjaHJvbWUyBggAEEUYOTIGCAEQRRhA0gEKMTQ1NTBqMGoxNagCALACAA&sourceid=chrome&ie=UTF-
What is more puzzling is to see a light helix rotating upstream, in a flowing
river, or more improbably, up a stream of water descending from a faucet. Here
is one such demo:
https://www.youtube.com/watch?v=RHFZ4iQKza0
Another "anti-grav" demonstration involves a slinky spiral wire toy.
If this has one end weighted with say a roll of masking tape and dropped from a
height say 20 ft. so that it extends close to the ground, but a few feet above,
the effect of dropping the top end is surprising: The bottom remains in place
until the slinky closes, then it drops rapidly.
https://www.google.com/search?q=experiment%3A+drop+the+foot+of+a+weighted+slinkey+from+a+high+spot&rlz=1C1CHBD_enUS945US945&oq=experiment%3A+drop+the+foot+of+a+weighted+slinkey+from+a+high+spot&gs_lcrp=EgZjaHJvbWUyBggAEEUYOTIG