The SAT Question Everyone Got Wrong

After 6 months is it light or dark on earth?

i got 4 too as a hunch and was very sure im wrong when the questions came out

Nice video

Great job at trying to confuse people! There is nothing magic about two discs (or gears or pulleys) rotating when they are tied together. Their mating circumferences magically change as rotation occurs! How far one rotates with respect to the other is only a function of their circumferences (circumference being a function of pi times diameter or pi times 2 times radius). Please note that one revolution in circular motion is defined as a point on the perimeter moving through 360° or 2 pi radians of rotation. Your attempt of deception with the coin is easy to spot as the coin being rotated only travels through part of 360° degrees and hence is not completing one "revolution" or "rotation" when the head is top up. The mathematical solution to the problem of how many revolutions does a disc of 1/3 the radius of a mating disk make when revolving around the larger disc is as follows: let X = number of rotations. Then with no slippage between the disks the smaller will travel a distance of X(2)(pi)(1) in traveling around the circumference of the larger so X(2)(pi)(1) =2(pi)(3). The number of rotations, X, therefore = 3.

What is the actual message or purpose of this video?
I'm still not convinced the initial problem statement and answer is wrong. As this video progresses it changes the initial problem statement from how many times does the smaller circle rotate when traveling around the larger circle. The answer is still correctly 3 times. See the inital question refer to distance travelled at the contact point. The so called coin paradox theory is exactly that, a theory. See when you change the perspective it looks like the coin is rotating one more turn, but it actually doesn't. The theories and problems being solved here have deviated from the initial question.

Deviation 1. Perception of 4 rotations. In this perspective the coins orientation is also changing as the surface of the larger coin is not linear. So as the smaller coin rotates it's orientation is also changing. But if you draw a dot on both coins and count the rotations from that, the smaller coin only rotates 3 times. Go on, try it.

Deviation 2. Orbit. In this perspective you are changing the problem statement to that of orbit. The problem statement here is how has the centre point of the smaller circle travelled i.e. orbited the larger circle. But the initial 2piR is still true, because the centre point has meant the diametre has now changed in a way (the reference or contact point has shifted). You added the diameter of the smaller coin to the larger coin.

As the video goes on we shift from rotation to orbit, to degrees in a circle to time to orbit. While all this might be interesting and great to explore, I'm not convinced the initial Q & A was wrong.

The problem is that the test question did not specify the reference frame. 3 is technically correct from the large circles rotating reference frame. Problems like this are common in physics and engineering.

OMG i said 4 :)

I got it right lmao. As soon as I read the title that ALL got it wrong, the only possible conclusion is that the answers are ALL wrong.

I nailed the first question! It felt easy😊. Ready to quit.

To me, the answer was obviously 4, not 3.
The reason is -- 3 times for the ratio given, PLUS one for going around the circle.
So, if the ratio was 7 to 1, then the answer would be 8.
For 1 to 1, the answer is 1+1, or 2.

I think people are afraid to say it. But this is an unnecessary complication of a simple problem. The answer is 3.

It is surprising how someone can get confused on what the question actually meant!

A really vivid way to do this is to unroll the big circle, see there are 3 rolls of the little circle to go that length, and then reroll the big circle with the little attached to the rolling end to see the little curls one more time.

Interesting they didn't just give everyone the mark for free when they discounted the question. Recently in a uni physics course of mine one of my friends proved an engine PV diagram used in a question impossible (yielding 2 different answers but the system didn't follow the laws of physics in the first place), everyone was awarded the mark for free and no scaling ocured.

The quarter went exactly one revolution around the other quarter, not 2!

When you mentioned that scraping the question would scale the score up or down... well those who got it wrong would scale up and those who got it right would scale down... and absolutely no one got it right. so we r good right?

but on the grand scheme of things, if everyone competing for the same college entrance took the same test, the ranking of all students have not changed. it would only matter if you are comparing with those who took another version of the test, which is never going to be 100% "fair" anyways.

I got 4.

This will be extremely cool to show my kids and experiment with, thank you for giving me another thing to share with them, it will look like magic at first lol, then the explanation will come in.

2pir

Comment before watching the full video: 9/2.

I have a question related to fluid mechanics.
Q:-)
If I have a container of given dimensions with water filled upto brim and placed on frictionless surface . After filing water I open the hole at bottom of container as a result it moves forward.
Then Can we find the velocity time function for the container.
And total displacement till water ends .
Assuming area container >>>>>> area of hole.

I guess it all comes down to whether you consider the rotations relative to the point of contact with the surface of the centre coin, or the actual number of rotations.

Hi everyone, this is a remainder to tell u that we are currently living through a genocide. Have you seen the recent posts from journalists in Gaza? They have essentially said their goodbyes, Pls keep standing in solidarity with Palestine, now more than ever we must do all we can within our power to help, never lose hope! And take care <3

The question is poorly configured. The fact that the test provider didn’t figure this out speaks volumes. When 300,000 take it and no one gets this question right it screams there is something wrong. With the question.

Array starts as zero.
NO IT STARTS AT ONE!
Same kind of torture 😂

got it right. if you calculate for the center of circle A not the inner edge then the radius of B is actually 4x not 3x.

I love to learn about things that happen counter to intuition. It's like a little window into reality itself.

The took something I understood intuitively to something I no longer understand.

c.

D right?

Just looking at it, it should be obvious it's (F) - four turns.
Same principle as planetary rotation - especially the earth where solar, what we see as our days, and celestial years have different numbers of earth rotations.

The second half was cool - it might make a good introduction to the principles of epicyclic/orbital gearing, using radians in math', and we use it quite often in engineering,

Well that was obvious. C2 / C1 + 1. Replace C with R or D if you like.

YOOOOOOO, I assumed 3 but i knew it was 4 from uust my eyeball 😈😈😈

But... like ALL standardized tests, which answer is the MOST correct. Of the possible "right" answers of 4, 3, and 1...only one of those is listed, ergo B is the answer.

gg

Feeling the totalizing sensation of confusion, anxiety, frustration, bewilderment, and pure rage wash over me at the sight of a single standardized test math question, paradox or not, reminds me why I tanked the math portion of the SATs and ended up in the botton 1 percentile while ending up in the 99th percentile for language. Got that exact 50% bell curve because of it.

I knew they were all wrong but didn’t know how! Thanks for explaining so well :))

So sad this only has 3.4M views while a Mr Beast's video has 100M :(

Today they would call you racist, homophobe, climate denier and a trimpster and destroy your future rather than admit they are wrong. And that's all sciences today!

you can also arrive at 4 by seeing how much would the center point of A have to travel to reach its origin, the radius of that movement will be equal to radius of B + radius of A.

Wow that information on astronomy was great. I never understood the difference between solar time and sidereal time but you explained it really well.

Happy to have figured it out prior to see the video. Of course I arrived at it because I knew the trivial answer wasn't the correct one. During the test I'd answer 3.

Real question is, who cares?

I have a headache.

Soo what did SAT marked

I guessed E

9