 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.
 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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