The SAT Question Everyone Got Wrong

“I was amazed how badly it’s worded,” literally half of the SAT problems.

To all the 1st posters: YouTube takes up to 15 minutes to gather data on a video before showing stats. Everyone in the first 15 minutes all think they're first.

Having the small circle rotating 3 times with the camera rotating is the best intuitive explanation of what's going on I've ever seen for something like this

I am currently 6 weeks from earning a Purdue Aerospace Engineering BS, I have completed the requirements for a physics minor, ive taken 2 graduate level astronomy courses and a graduate level Space Traffic Management course that dealt with sidereal time on every assignment, but this is easily the best conceptual explanation of sidereal time I have ever seen. Genuinely incredible educational content, I'm blown away.

This was a mentally challenging video to watch first thing in the morning. I'm awake now

That part about the circle rotating around the triangle was mind-blowing. You instantly understand why it's not the same if the circle rolls on a flat line or rolls on a curved line

This explanation is the best i have found. The idea of the distance the centre of the planet circle travels and then deriving ratios makes the most sense to me and your graphics helped me to grasp this. It's fascinating. Not too mention the perspective element influencing the answer!! What i didn't realise is that the extra rotation is accounted for as well if observing from the perspective from the centre of the "sun" circle by the fact that the observer has to rotate once to continuously observe the "planet" circle

I wasn’t the best at math in high school not because I didn’t get the right answers but because I could visualize the problem. My problem is I couldn’t show how I got the answer. This one is easy. In my head I just rolled it around and got the right answer. This is geometry for me. Visually simple.

I was confused for a second until I realized that if you set the radius of the big circle to 0, or in other words rotate the smaller circle around a point on its circumference, it takes 1 full rotation for the circle to end up back at the start.

In college, I took a poetry class and once had an answer marked wrong on a test. Confident in my response, I reached out to the poet themselves, who affirmed I was right and even communicated this to my professor. Despite not being a fan of poetry, that moment made me quite proud!

This concept is quite important while solving Rotation problems in Physics. Instantaneous Centre of Rotation, given that it is pure rolling i.e. there is no slipping at the point of contact. It at this centre of instanteous rolling the entire circle or rigid body is pure rotating. Thanks for sharing.

I appreciate every one of your videos, they always make me think, and sometimes make my head hurt. Thank you.

The 1872 novel “Around the World in Eighty Days” had a plot that depended on this kind of situation. Phileas Fogg traveled around the world eastward, against the earth’s rotation. Though initially he thought he’d missed the 80 day deadline by some hours, in fact only 79 days had passed in London. One extra rotation had passed beneath his feet. He won the prize, married the girl and lived happily ever after.

Another fun way to conceptualize the N+1 is to ask what happens if the circumference of B is 0. A still has to rotate around that point, one time. Great video.

Honestly one of the best random fact and knowledge shows I have seen in quite a while.

no wonder everyone got them wrong, there was no correct answer

I loved the "I hope so" answer from Doug at the end. It highlights the most important lesson I learned during my education: "I might be wrong."

It makes the story even better to know that one of the students who found the SAT error became a mathematician.

I've just found your channel and it is really brilliant. Keep up with the good work :)

This is really interesting! I initially interpreted it as the revolutions answer (1) and was immediately very thrown off by the answer options. Very cool to learn about this type of math problem!