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Can you solve this 2014 US Physics team qualifying exam helicopter rope problem?
Posted on 10/28/21 at 11:08 pm
Posted on 10/28/21 at 11:08 pm
quote:
The story of a controversial physics question on the qualifying exam for the 2014 US Physics Olympiad team. How does a uniform cable beneath a helicopter hang?
LINK
Can you guess the answer without watching the video first?
This post was edited on 10/29/21 at 3:44 pm
57
Posted on 10/28/21 at 11:10 pm to euphemus
D is my guess
But it seems that it would oscillate between C&D, so maybe E.
But it seems that it would oscillate between C&D, so maybe E.
This post was edited on 10/28/21 at 11:12 pm
Posted on 10/28/21 at 11:10 pm to euphemus
All of those drawings are wrong. When a helicopter shaped like that flies forward, the front is tilted forward.
Posted on 10/28/21 at 11:11 pm to euphemus
B is the correct answer
Posted on 10/28/21 at 11:11 pm to euphemus
I’m going to guess that since the helicopter is moving at constant speed, there is no acceleration at all in this system and hence no force to bend the rope.
It hangs down straight.
It hangs down straight.
Posted on 10/28/21 at 11:11 pm to euphemus
I’m thinking B because of tension on the line created by drag and the fixed attachment point.
This post was edited on 10/28/21 at 11:13 pm
Posted on 10/28/21 at 11:13 pm to euphemus
C
Posted on 10/28/21 at 11:14 pm to euphemus
B is correct
Posted on 10/28/21 at 11:14 pm to euphemus
E.
Sin wave.
The end of the cable takes less force to move than the beginning.
Sin wave.
The end of the cable takes less force to move than the beginning.
Posted on 10/28/21 at 11:14 pm to euphemus
C
Posted on 10/28/21 at 11:15 pm to euphemus
My intuition said B in a vacuum, D with air resistance
I’m a ME so if that’s wrong I will have to bare great shame
I’m a ME so if that’s wrong I will have to bare great shame
This post was edited on 10/28/21 at 11:17 pm
Posted on 10/28/21 at 11:18 pm to euphemus
D
Posted on 10/28/21 at 11:19 pm to Ross
Equal wind resistance pushing laterally against the length of line while in motion... combine that force with the constant weight of the line pulling down
Posted on 10/28/21 at 11:20 pm to Ross
(no message)
This post was edited on 11/10/21 at 11:47 pm
Posted on 10/28/21 at 11:24 pm to euphemus
Non of the above. That is not a helicopter.
Posted on 10/28/21 at 11:24 pm to euphemus
288
Posted on 10/28/21 at 11:27 pm to euphemus
B.
Force is the same throughout the line. Only difference is length from a fixed point, which is linear, which gives you a linear line.
Pure guess since it’s been 6 years since I took the PE and 10 years since I’ve done static equation calcs.
Force is the same throughout the line. Only difference is length from a fixed point, which is linear, which gives you a linear line.
Pure guess since it’s been 6 years since I took the PE and 10 years since I’ve done static equation calcs.
Posted on 10/28/21 at 11:31 pm to euphemus
The answer is B. Seems pretty straight forward. Now I’ll watch the video to find out if I am an idiot or not.
Posted on 10/28/21 at 11:32 pm to euphemus
I guess the question is how heavy is the cable and how fast is the helicopter moving forward.
If the cable is heavy and the helicopter is barely moving forward then I would say A
If the cable is heavy and the helicopter is moving forward at a good pace then I would say B
If the cable is light and the helicopter is barely moving forward then I would say C
If the cable is light and the helicopter is moving forward at a good pace then I would say D
Don’t know where the hell E comes from
If the cable is heavy and the helicopter is barely moving forward then I would say A
If the cable is heavy and the helicopter is moving forward at a good pace then I would say B
If the cable is light and the helicopter is barely moving forward then I would say C
If the cable is light and the helicopter is moving forward at a good pace then I would say D
Don’t know where the hell E comes from
Posted on 10/28/21 at 11:36 pm to euphemus
C
The angle of the dangle is inversely disproportionate to the heat of the meat.
The angle of the dangle is inversely disproportionate to the heat of the meat.
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