Kind: captions
Language: en
[Applause]
you pitch
that hey how did you do that that was a
hard one because uh this ball is a
little bit magic it's got a bit of
string glue to the left side of it to
make the ball curve to the left why is
that and that's because the air that's
flowing from the front of the ball
around to the back Encounters this
seam becomes turbulent and turbulent air
air is known to stick to the ball longer
than smooth or lamin flow and so the air
is deflected this way to the right on
the ball and therefore there's a force
on the ball to the left and so it curves
this is quite a light ball so it curves
a long way uhuh but uh on a cricket ball
the seam isn't on one side it seam is
down the middle correct it's spinning in
such a way that the seams inclined at an
angle to the direction of motion of the
ball I see in which case air coming
towards the ball will flow smoothly
around the smooth side and separates
from the ball air flowing On The Rough
Side the same side becomes turbulent as
soon as it encounters that seam gets
deflected to the left mhm and therefore
the ball gets deflected to the right so
you basically make a rough side using
that seam by angling the seam with a
cricket ball with a cricket ball or you
can have a rough and a smooth side
because as time goes on during the game
one side gets rougher than the other the
players maintain the smooth Side by
polishing it or wherever as if as if
they're scratching themselves right uh
and then you don't really need the same
for to have that effect cuz the effect
is just a rough side and a smooth side
so a ball will always swing towards the
Rough Side then it does but how does
someone swing a baseball then uh that
relies on the Magnus of effect normally
so if the if the spin is about a
vertical axis it'll either curve to the
left or curve to the right that's a
curve ball uh
exactly however uh there's a pitch ball
known as a scuff ball that people don't
like to know about CU it's
illegal and if you're roughing up one
side of the ball surreptitiously without
anybody noticing it and then toss it uh
it will curve a long way just like the
cricket ball it'll curve towards the r
side correct however there's an effect
discovered just this year which is
fairly obvious when you think about it
you can have a smooth patch on a
baseball but I mean the seam seems to be
symmetric everywhere so how can you
really have a smooth patch what you do
there is to make sure the axis passes
through a spot which is a large distance
from the seam in other words right about
there it's about 1 in away from the seam
and if it rotates about that axis then
you've got a big spot that's always
smooth on that side got a Smooth Spot as
opposed to a rough spot and so it swings
away from the Smooth Spot it does and I
can show you that in slow motion ah so
you've tried this out with one of your
poly siren balls I have so that you can
see the effect more dramatically but
it's also on film from a real baseball
match in April this year it was filmed
and notice for the first time that it's
curving the wrong
[Music]
way
so who was it who explained this
effect
me you were the first person to explain
how you can cause a a baseball to swing
in the opposite direction I took an aie
to show uh show The Americans how it's
done exactly uhhuh well why don't we uh
why don't we play a bit of ball but with
that thing I don't think you can swing
that as much I can't yeah so let's give
it a
shot