Have you ever wondered why ice skaters can just speed themselves up
by simply bringing their arms in?
Well, it turns out there’s a thing called moment of inertia,
which is how difficult it is to spin something.
So when the mass is close to the center,
it’s easy to spin. When it’s far away,
it’s more difficult. So you can see,
when the mass is brought in,
I’m easier to spin, so I spin faster.
When the arms are brought out,
I slow down cause I’m more difficult to spin.
The overall thing that stays conserved here
is this thing called angular momentum.
I have a set amount of it,
it’s not changing.
The only thing that is changing is my angular speed
or how fast I’m rotating. An angular momentum is both of these things.
This moment of inertia is how difficult it is to spin
and how fast I’m spinning.