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Physics riddle

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Thread replies: 46
Thread images: 3

File: UK_map1.png (111KB, 1666x1924px) Image search: [Google]
UK_map1.png
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Hey guys, today the physics prof. asked us this question and I have no idea how to answer it.

>If the UK switched from driving on the left to driving on the right, would a day be longer or shorter in the UK?

We don't have to calculate anything, we just have to answer longer or slower with a brief explanation.
>>
Tell him that the two events aren't related.
>>
>>8474064
It would obviously get shorter
All these people bitching about the change will be amusing enough to shorten my days for a good while
>>
Is that "or" inclusive or exclusive
>>
>>8474072
the contents of this post to be entirely frank brothers
>>
>>8474072
exclusive
>>
>>8474072
>>8474064
This, the answer is "no". He is asking if the day would have another length if you swapped sides.
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>>8474064
The clockwise parts of ring roads just got longer and anticlockwise parts shorter.
Therefore something
>>
>>8474131
You might be onto something.
>>
>>8474064
The day would get shorter, the northern hemisphere is currently transitioning towards a winter solstice meaning days are getting shorter for the UK.
>>
Slightly longer from the subtle change in the tilt of the earth.
>>
how the hell could those two things possibly be correlated, are the roads specialized to favor one direction over another?
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>>8474172
Can you explain why would the subtle tilt occur?
>>
>>8474176
roads lined westward have cars moving in opposite directions. assuming the metal in the cars came out of the earth in the first place, their movement causes equal and opposite movement on the planet?
>>
>>8474064
i am having trouble thinking of any force that is not in equilibrium
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>>8474191
I still don't really get it. I'm sorry, I'm asking a lot, but can you explain it like if I was a first grader?
>>
ask him what his wife thought was longer, the day or your cock.
>>
File: 1469138325896.gif (359KB, 640x636px) Image search: [Google]
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>>8474064
>the UK switched from driving on the left to driving on the right
>the UK

protip: it has nothing to with cars

answer: shorter

good luck
>>
My thinking is, with left side driving it means that on average, cars travelling clockwise have further to travel than cars travelling counter-clockwise, meaning that the UK's angular momentum due to cars is slightly more clockwise (most car journeys are basically cyclical so this seems like a reasonable assumption).

Switching sides would flip this making the UK's car AM be more counter-clockwise, the same as the earth's spin when viewed from the northern hemisphere so it would spin faster making the day shorter.
>>
>>8474090
This. The question isn't: would the days be longer, or would the days be shorter.

The question is, would the days be [longer or shorter] i.e. would there be a change.

The point of your prof asking is to get you to pay attention to how questions are phrased.
>>
>>8474131
I started thinking this as well, but I don't think we can really assume that it matters due to the rotational invariance of the roads. I was going to say that the longer left turns would force cars to push with the turn of the Earth more for North-facing roads turning to Westward ones, but every change of this form would be counteracted by the approximately equal change for South-East turns. Maybe it matters that turns closer to the equator will be applying more torque since they are further from the axis of rotation?
>>
>>8474260
>shorter
I really like those candy balls from that guy
>>
>>8474406
You're getting warmer. For most roads it wouldn't make any difference because the people going out one way will drive in the opposite direction when they go home. Is there anywhere where this isn't true?

>>8474344
>>8474090
Nope. This was set as an exam question in a general physics class I had at uni. The answer is not no.The point is to solve the problem, not deconstruct the question.
>>
>>8474513
>for most roads
Then for what kind of roads would it make a difference?
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>>8474281
This seems to make sense
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>>8474513
Is it at all significant that many people drive home at night but leave during the day? It would mean nights change inversely to the change in day length, but the question only refers to the day. So, that could be a source of symmetry breaking.
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>>8474523
That's what I'm asking OP to think about. If he's truly stuck I'll reveal the answer but these things are always more satisfying if you get them.
>>
>>8474554
It's not really what they want but it's not a stupid suggestion. Think about it, how much data would you need to work out in which direction there was a bias, if any? The question was asked because it is answerable.

Quick question: Where are you from OP?
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>>8474572
Yeah, I have ruled out many ideas because I know I am overthinking it. I am struggling to see the forest through the trees.
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>>8474563
I'm trying to figure out any kind type of road where this applies, roundabouts are not an option, I have nothing else.
>>8474572
I'm from Hungary
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>>8474064
No
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>>8474576
It's a tough question, I didn't get it without help. Are you from the UK btw?
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>>8474580
>roundabouts are not an option
Why?
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>>8474594
>>8474406

I thought when you said you are getting warmer you meant that it has nothing to do with them, but something else.
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>>8474589
Nope, just a colonyfag. Would being from the United Kingdom help? Maybe there is something I don't know.
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>>8474064
>would a day be longer or shorter in the UK?
Why the fuck does he say "in the UK?" How would the length of their day be different from anywhere else?
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Roundabouts would switch direction and when a car goes around in a roundabout, the southest part of the roundabout is closer to the equator, aka farther away from the axis of rotation, so it applies more torque on Earth.
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>>8474598
Sorry, I guess I threw you off. When I said you were getting warmer I mean it was good to think about what journeys would cancel.

>>8474600
I guess the jig is up. It's roundabouts. Some parts of the states don't have them hence why I was asking.

The idea is that all journeys on normal roads will cancel (when averaged in time) as people return home. With roundabouts this is not true because everyone regardless of where they are headed drives the same way round the roundabout.
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>>8474604
Everywhere, not just in the UK, my bad.
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>>8474616
Oh, interesting! Ironically, I wasn't sure if you guys had them or not. This is a good riddle.
>>
File: Untitled-1.png (43KB, 1469x550px) Image search: [Google]
Untitled-1.png
43KB, 1469x550px
Model the whole country as a bunch of square blocks. Pic related.
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>>8474064
You studying at cambridge? The important thing isn't to idealise roads as lines and to remember that traffic flows both ways down most roads
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>>8474616
Sorry if I sound stupid, but will the day be shorter or longer then?
What's the short answer, you have saved my day dude, a thousand thanks
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>>8474260
The U.K. is now America. Driving on the right and 6 hours behind, therefore shorter

>302 IQ
>>
>>8474064
lets assume for some reason we have not figured out yet there was a total force due to the switching of driving directions.

you would have to show that this has any effect on the continent because in my mind at least (not that familiar with geology) uk is connected to some part of the earth which might be forced to stay in place due to static friction.
>>
>>8474064

Earth's rotation is slowing slightly with time; thus, a day was shorter in the past.

Therefore the answer is 'longer', because it might only happen in future
Thread posts: 46
Thread images: 3


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