A Derek Muller and UCLA Prof. Alexander Kusenko -- Downwind Physics Wager

[Jay_]

Derek Muller is the Veritasium YouTube channel host and he had a wager against UCLA professor Alexander Kusenko on whether a unpowered car going downwind can go faster than the wind.

Derek Muller said it can go faster than the wind, while Alexander Kusenko said it only seems that way because the wind slows down and the car continues to move on its own inertia.

I guess many of you must have been following this wager and the surprising thing is Derek Muller won this wager for $10,000.
https://www.iflscience.com/physics/youtuber-derek-muller-won-a-10000-physics-bet-against-professor/

This leads to my question:
Do we not really understand the kinematics of the wind forces and transport phenomenon fully enough to model this correctly and obtain the right understanding without Derek running an experiment? Or was the professor just not taking everything into consideration when he thought of his explanation here?


What wasn't considered when Alexander Kusenko was explaining that was explained?

 

[cjl]

It's really not surprising to most long term members here, and it's been discussed extensively many, many times. There's a currently active thread that discusses this exact video and wager here (the video discussion is a couple pages in), but there are older discussions here, here, here, and I'm sure several other places that didn't show up in my 10 seconds of searching. As you can see, this was really a hot topic about a decade ago here, and has been pretty settled here ever since, but part of what makes it so intriguing to so many people is that it is very counterintuitive, which leads a lot of (even very qualified) people to confidently proclaim it must be impossible.

We definitely understand the behavior of propellers and kinematics well enough to easily analyze such a vehicle, and show that it is possible, but usually, people don't bother to fully analyze it in a correct and comprehensive way before just declaring it impossible, hence the (extended) discussions and wagers.

 

[Jay_]

I guess the main thing is like you mentioned they don't bother to fully analyze it. I will look at the other links. An interesting conversation on this would be understanding the conservation of energy in this scenario.

 

[cjl]

Yeah, it's interesting, and you do have to be careful with keeping your frame consistent when analyzing, but it does all work out.

(Here's yet another discussion thread if you want to see yet more talk about it, and it also contains links to even more yet older threads).

 

[berkeman]

Thanks @cjl for posting the links to all of the discussions (including the very good current one) -- you beat me to it.

@Jay_ please continue any discussion in the current thread. Thank you.