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[SOUND EFFECTS PLAYING]
[MUSIC PLAYING]
Hey, Space Timers.
We don't have a whole episode for you this week,
but I did want to present you with a challenge question that
relates to a recent episode about gravity
and also to some other episodes we've
got coming up in the future.
You guys ready?
In our gravity episode-- that you can click over
here to view-- we referenced the balloon video from Smarter
Every Day, which you should check out if you haven't seen.
Now, in that balloon video, there's
a helium-filled balloon attached by a string
to the floor of a minivan.
Let's take Dustin and his kids out of the minivan
but leave the helium balloon in.
Now, suppose that I dropped that minivan off a cliff.
And at the same moment that I let go,
I want to cut the string that holds the helium
balloon to the floor.
Here is the question-- as viewed from inside the minivan,
where does the balloon go?
Pretend the van is completely airtight with regular air
inside but that you can ignore air resistance outside.
So for simplicity, let's just say that the van
is falling through a vacuum.
You guys got it?
OK.
Do not put your answers in the comments.
Instead, email them to pbsspacetime@gmail.com
with the subject line "BALLOON CHALLENGE,"
and the subject line has to look exactly
like this because we're filtering
these emails automatically.
Submit your answers with explanations before next week's
episode airs on Wednesday.
That gives you about a week to think it through.
We'll be giving away t-shirts to some randomly chosen people
from among those who submit correct answers
with correct explanations.
I'm looking forward to your emails, but as always,
thanks for tuning in.
And I'll see you next week with the answer to the challenge
and a fresh episode of Space Time.
[MUSIC PLAYING]