Kind: captions
Language: en
all right you've made your prediction
and we've tied a tennis ball to the base
of the slinky here and now we're going
to extend it and drop it and see what
happens to the tennis
ball the heavy weight of the tennis ball
is going to stretch the spring a little
bit further so I'm going to cheat a
little bit by shortening it a fraction
at the top all right so we can see both
the top and bottom ends sounds good and
on the count of three I'll drop it ready
one two three
whoa what did you see there it fell very
rapidly I need to look at that
inflamation to see what's going on all
right let's go to the slow motion
[Music]
footage so when you watch that you see
that the tennis ball it really remains
stationary until the whole Slinky is
collapsed above it correct the the uh
White force acting on the tennis ball is
counted by the tension force acting
upwards until the information travels
down the slinky that the tension has
changed it's really quite strange
because it's as though the falling
Slinky can support the tennis ball in a
way uh that's what it looks like and
indeed that's what it's
doing I just find that so amazing and so
counterintuitive we study physic because
lots of unexpected things happen and
it's those unexpected things that make
physics interesting it's uh it's really
strange it's like uh if you were falling
out of a plane and you had a big enough
Slinky you might uh be okay for a little
while I wouldn't try it though you're
better off with a parachute exactly all
right well thanks Rod much appreciated
your uh your help today it's been
fun