Oh yeah.
CREW: Oh yeah.
Yeah?
CREW: Yeah.
Do you know what I'm talking about?
CREW: [INAUDIBLE] go faster and faster.
Yeah, I've seen people do this before.
But you've never done this before?
No.
Michael, when did you grow up?
The '90s.
We're, like, pretty close.
The 1790s.
Hand-clapping hadn't been invented yet.
Can you tell us--
MICHAEL: Robert Clap--
--the history?
Robert Clap, one day he was like, that was amazing.
And everyone was like, do that again.
He was like--
Are you serious right now?
I'm totally serious.
This is the actual history?
Yeah, I tell the truth at all times.
I 80% believed Michael until I realized, Michael Stevens
didn't grow up in the 1790s.
Can't fool me.
But that's not why you're here.
You're here because you want to see
me challenge our guest to some physics, puzzles, and riddles.
And I better introduce him because you might not
know who he is, despite the fact that he has a channel
name across his chest and because he
has the most viewed science YouTube
channel on the platform.
So better get do it.
Hey, I'm Dianna.
You're watching "Physics Girl".
I'm here at the "Vsauce" warehouse with Michael Stevens,
the host of "Vsauce".
You agreed to be asked some puzzles and riddles, logic,
physics, that kind of stuff.
I didn't just agree.
I insisted.
You did.
I love puzzles because I'm not that great at them,
but afterwards I always feel like a better person
because I've learned something.
Should we get to it?
Let's do it.
We're going to start with some warm-ups.
Then I hope the warm-ups are easy because you're calling
them warm-ups like I'm supposed to just squish them.
But they're still riddles and they're still puzzles.
They're just the ones that are like,
you either get the concept or you don't.
OK.
I have a ping-pong ball, and I think that I can throw it such
that it will suddenly stop and turn around and come
right back at me.
How could I do that?
How could you do that?
You know the drill.
Pause the video here if you want to think about it for yourself
before we continue on with the answer.
So here's the question again.
How could I throw a ball so that after a bit
it stops, turns around, and comes right back at me.
And it's not bouncing off of anything.
Nope, not bouncing on anything.
Right-- right.
I'm assuming it has to do with, like, the spin of the ball.
At some point it will have slowed
down enough that its spin becomes the major component
of its motion.
That's a good guess.
I'm going to do it such that no matter my technique,
no matter my skills, I can always
get it to come right back at me.
Ah, so just throw it straight up.
Yeah.
Got it, yeah.
See, yeah, that's one of those great ones where you're like,
oh, I think of throwing as been a horizontal action.
As being horizontal.
The weird thing about this whole situation
is that when you throw a ball straight up in the air,
it'll stop instantaneously at the top.
But that means that right before and right after,
like a millisecond, a microsecond before
and a microsecond after it'll be moving up
and then it'll be moving down.
How is it possible that a ball is only stopped for an instant?
Such is the nature of continuous motion.
Is this one of those situations where I'm like,
this is so weird and everybody else is like, no it's not.
That's just how the world works.
Moving on.
Next.
DIANNA: Next one.
Michael, you've got a glass of water.
And over here, imagine that you have an ice cube.
And inside the ice cube it looks normal
because it looks like everything is clear,
but inside of it it's got a little diamond
frozen in the middle.
Got it?
MICHAEL: Great, beautiful.
DIANNA: Yeah.
And then you drop the ice cube into the glass of water.
Now, when the ice cube melts and the diamond falls
to the bottom of the glass--
because carbon in diamond form is more dense than water--
does the water level go down, go up,
or stay the same from the level it was at when the ice
cube is first placed in there?
Very good question.
All right, so let's work through this.
So--
And that's where we're going to cut
because I know you love being on the edge of your seat
because it's so good for your brain juice
to have to wait just one more day
to think about the answer to the riddle
until you get a video with the answer and maybe a bonus riddle
if you guys leave enough comments with your guesses
for the answer to this riddle.
Or, in the meantime, here are three other things
I'd love to hear from you.
Number one, I'd love to hear comments
about your favorite other physics riddles or puzzles.
Number two, I'd love to hear your everyday mysteries
for the everyday mystery series using the hashtag
#everydaymysteries in the comments.
And number three, if you have them,
tweet me your photos of the Physics Girl T-shirt.
I haven't gotten any photos from any ladies
yet, but thanks to these physics-y gentlemen
for sending me their photos.
And that's it.
Happy physicsing.
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