a Newton’s Cradle is a well known
apparatus that demonstrates Newton’s
third law of motion that for every
action there is an equal and opposite
reaction today we’re going to be
building a scaled-up Newton’s Cradle
using billiard balls you’ve probably
seen and played with those little
desktop toys made of like five silver
marbles that just swing back and forth
and make Pleasant clacking noises
they’re used for stress relief or just
the background noise today we’re gonna
be building a larger one of those and
instead of those small metal balls we’re
going to be using billiard balls here’s
the building plan we’ll have two frame
pieces attached to the base and to each
other near the top we’ll have some hooks
that we can run our lines through along
with some pegs that will help us make my
nude adjustments to start we’re gonna
build two pieces of frame and each one
is going to be made of three pieces of
our 2×2 each of those pieces is going to
be 18 inches long to start so let’s get
cutting
one of these beams will be the top piece
and then we’re gonna have two legs
coming down on the sides of it so it’ll
basically be like that and what angle we
have this set up is pretty subjective it
can be kind of whatever you want so I’m
just going to take one measurement and
then cut all of the pieces to match
[Music]
beautiful we just need to trim the
bottom so that it will sit flush on the
we’ve got all our pieces cut now we’re
going to secure them together we’ll make
two of this shape
excellent each of our billiard balls is
pretty much exactly 2 and 1/4 inches in
diameter so what we need to do now is
drill some holes into the top of each
support beam five of them because we’re
gonna have five different billiard balls
and of course each hole needs to be two
and a quarter inches apart these four
dots in this one cross point is where we
will drill the holes to attach our hooks
and hang on the other side
[Music]
[Applause]
[Music]
these holes we just drilled are going to
have these hooks in them however when
you’re making a Newton’s Cradle it’s
actually quite important that all of the
balls in the cradle line up perfectly in
all three dimensions they can’t be too
far apart from each other they can’t
have the strings leaning toward each
other so that there’s too much pressure
holding them together and that can be a
really tricky thing to do however the
system I have devised seems to work
pretty well for being able to adjust
where they hang so we’re going to have
these five hooks but we’re also going to
have five sort of tuning pegs that will
let us adjust how the billiard balls
hang we’re just going to be using some
pieces of dowel as the little tuning
pegs will have the hook a little bit
higher the line will come from the
billiard ball up through the hook and
then back down to the peg which will
install a little below the pegs that way
all of the pressure should always be on
the hook we regardless of where on the
swing angle the ball is
now we want these to be sturdy as they
sit about eight inches apart so what
we’re gonna do is take some of our scrap
pieces of 2×2 cut a couple of lengths
that are eight inches long and attach
hmm I think news needs to be black we’re
gonna turn this black
[Applause]
to attach the billiard balls onto the
frame we’re going to be using these even
smaller little eye hooks and some
fishing line and to get these little eye
folks attached to the billiard balls
we’re going to use a very small drill
bit we’ll drill two holes into each
billiard ball and then screw the hooks
in and then attach the wires onto those
[Applause]
[Music]
we’ve got all the hooks installed onto
the billiard balls and now we need to do
is attach the cords and for that we’re
using some thin fishing line the knot
that I’m using is called the Palomar
knot and it’s designed for attaching
fish hooks line you start out by just
making a loop on one side with I’ve got
plenty of extra here if you’re actually
doing this on a hook you wouldn’t need
nearly that much extra that you will on
this you’ll see why
so that loop pushes down through the eye
and we’ve got these two sides and that’s
where the end of the doubled over
portion is and we’re just going to tie
this in an overhand knot overhand knot
right there and what we need to make
sure is that the loop on this side of
the overhand knot is big enough they can
fit all the way around the billiard ball
and then we pull it tight you can cut
off all the extra it gets a little bit
more complicated when you attach the
second one because you still have to fit
it all the way around billiard ball but
you don’t want to catch the first line
in your knot and so you have to sort of
feed it through so I’m going to take
this loop wrap it all the way around the
billiard ball then I also have to pull
that out of the way before I tighten
this is gonna be part of our base it’s
going to go on top of this other piece
of plywood and that just is going to
give us a nice look to it
let’s go trim this down
now we need 10 pegs to fit in these
holes each one just about inch and a
half maybe 2 inches long make it an even
so that we can attach our fishing line
to these sort of tuning pegs we’re just
gonna drill a hole through each of them
now we’ve got all of our frame built in
it’s time to start attaching the
billiard balls doing anything too fancy
here just not on one side and then a
square not on the other side now by
twisting that peg I can shorten or
lengthen the line on that side and that
beautiful form or it’s not going to be
perfect but fortunately we have the
ability to adjust and get it closer at
this point I think we are ready to test
it out it seems properly calibrated
let’s see how well it works the Newton’s
Cradle is wonderful for demonstrating
Newton’s third law of motion which is
that for every action there is an equal
and opposite reaction billiard balls are
not very compressible and so all the
energy that enters into one side of them
tries to exit out the other side if it
can’t move if I pull back on the red
ball the orange yellow and green balls
for the most part stay in place and the
energy from the red ball is transferred
over to the blue the blue swings out
swings back and transfers its energy
back through the middle three and into
the red ball again this is not a perfect
system and in fact there’s no such thing
as a perfect system so some energy is
not transferred just the way we want it
that’s why we start seeing some swinging
motion and why it doesn’t continue
moving forever some of the motion is
transferred through the lines up into
the frame into the base onto the
workbench and it’s lost there a little
bit of the energy has actually turned
into heat as the billiard balls collide
with each other in a truly perfect
system the three billiard balls in the
middle would never move and the two on
the outsides would keep bouncing back
and forth forever that would also
require there is no air resistance the
little desktop toys usually use a
metallic ball which is
even better at transferring energy than
these billiard balls they’re also often
slightly magnetic which helps hold them
together if the energy from a swinging
ball isn’t pushing it out of line you
can make some really interesting
patterns by playing with this thing if
the line is swinging and then one ball
is pulled away and allowed to drop the
line will keep swinging but the outside
balls will bounce on and off random fact
the name Newton’s Cradle was coined in
1967 by the English actor Simon Preble
[Music]
by shortening the strings we eliminate
some of the play so it should last a
little bit better but we also have a
much shorter period which is the length
of time it takes the ball to swing from
one apogee to the other Newton’s Cradle
a fun toy to build and use I like trying
to figure out interesting new bounce
patterns with it overall I really enjoy
building it and it’s a good example of
Newton’s laws of motion and physics are
there other things you would like to see
us build demonstrating basic science
principles let us know down in the
comments as always if we use your idea
to make a video we will send you 25
bucks the fun’s not over that box of the
top will transport you directly to our
last video and you should check that out
the other box will show you what YouTube
thinks you need to be watching next and
if you aren’t subscribed to our channel
hit this bomb in the middle and that way
you never miss out on the fun don’t
forget to ring that Bell and we will see you in the next one talk to you then
apparatus that demonstrates Newton’s
third law of motion that for every
action there is an equal and opposite
reaction today we’re going to be
building a scaled-up Newton’s Cradle
using billiard balls you’ve probably
seen and played with those little
desktop toys made of like five silver
marbles that just swing back and forth
and make Pleasant clacking noises
they’re used for stress relief or just
the background noise today we’re gonna
be building a larger one of those and
instead of those small metal balls we’re
going to be using billiard balls here’s
the building plan we’ll have two frame
pieces attached to the base and to each
other near the top we’ll have some hooks
that we can run our lines through along
with some pegs that will help us make my
nude adjustments to start we’re gonna
build two pieces of frame and each one
is going to be made of three pieces of
our 2×2 each of those pieces is going to
be 18 inches long to start so let’s get
cutting
one of these beams will be the top piece
and then we’re gonna have two legs
coming down on the sides of it so it’ll
basically be like that and what angle we
have this set up is pretty subjective it
can be kind of whatever you want so I’m
just going to take one measurement and
then cut all of the pieces to match
[Music]
beautiful we just need to trim the
bottom so that it will sit flush on the
we’ve got all our pieces cut now we’re
going to secure them together we’ll make
two of this shape
excellent each of our billiard balls is
pretty much exactly 2 and 1/4 inches in
diameter so what we need to do now is
drill some holes into the top of each
support beam five of them because we’re
gonna have five different billiard balls
and of course each hole needs to be two
and a quarter inches apart these four
dots in this one cross point is where we
will drill the holes to attach our hooks
and hang on the other side
[Music]
[Applause]
[Music]
these holes we just drilled are going to
have these hooks in them however when
you’re making a Newton’s Cradle it’s
actually quite important that all of the
balls in the cradle line up perfectly in
all three dimensions they can’t be too
far apart from each other they can’t
have the strings leaning toward each
other so that there’s too much pressure
holding them together and that can be a
really tricky thing to do however the
system I have devised seems to work
pretty well for being able to adjust
where they hang so we’re going to have
these five hooks but we’re also going to
have five sort of tuning pegs that will
let us adjust how the billiard balls
hang we’re just going to be using some
pieces of dowel as the little tuning
pegs will have the hook a little bit
higher the line will come from the
billiard ball up through the hook and
then back down to the peg which will
install a little below the pegs that way
all of the pressure should always be on
the hook we regardless of where on the
swing angle the ball is
now we want these to be sturdy as they
sit about eight inches apart so what
we’re gonna do is take some of our scrap
pieces of 2×2 cut a couple of lengths
that are eight inches long and attach
hmm I think news needs to be black we’re
gonna turn this black
[Applause]
to attach the billiard balls onto the
frame we’re going to be using these even
smaller little eye hooks and some
fishing line and to get these little eye
folks attached to the billiard balls
we’re going to use a very small drill
bit we’ll drill two holes into each
billiard ball and then screw the hooks
in and then attach the wires onto those
[Applause]
[Music]
we’ve got all the hooks installed onto
the billiard balls and now we need to do
is attach the cords and for that we’re
using some thin fishing line the knot
that I’m using is called the Palomar
knot and it’s designed for attaching
fish hooks line you start out by just
making a loop on one side with I’ve got
plenty of extra here if you’re actually
doing this on a hook you wouldn’t need
nearly that much extra that you will on
this you’ll see why
so that loop pushes down through the eye
and we’ve got these two sides and that’s
where the end of the doubled over
portion is and we’re just going to tie
this in an overhand knot overhand knot
right there and what we need to make
sure is that the loop on this side of
the overhand knot is big enough they can
fit all the way around the billiard ball
and then we pull it tight you can cut
off all the extra it gets a little bit
more complicated when you attach the
second one because you still have to fit
it all the way around billiard ball but
you don’t want to catch the first line
in your knot and so you have to sort of
feed it through so I’m going to take
this loop wrap it all the way around the
billiard ball then I also have to pull
that out of the way before I tighten
this is gonna be part of our base it’s
going to go on top of this other piece
of plywood and that just is going to
give us a nice look to it
let’s go trim this down
now we need 10 pegs to fit in these
holes each one just about inch and a
half maybe 2 inches long make it an even
so that we can attach our fishing line
to these sort of tuning pegs we’re just
gonna drill a hole through each of them
now we’ve got all of our frame built in
it’s time to start attaching the
billiard balls doing anything too fancy
here just not on one side and then a
square not on the other side now by
twisting that peg I can shorten or
lengthen the line on that side and that
beautiful form or it’s not going to be
perfect but fortunately we have the
ability to adjust and get it closer at
this point I think we are ready to test
it out it seems properly calibrated
let’s see how well it works the Newton’s
Cradle is wonderful for demonstrating
Newton’s third law of motion which is
that for every action there is an equal
and opposite reaction billiard balls are
not very compressible and so all the
energy that enters into one side of them
tries to exit out the other side if it
can’t move if I pull back on the red
ball the orange yellow and green balls
for the most part stay in place and the
energy from the red ball is transferred
over to the blue the blue swings out
swings back and transfers its energy
back through the middle three and into
the red ball again this is not a perfect
system and in fact there’s no such thing
as a perfect system so some energy is
not transferred just the way we want it
that’s why we start seeing some swinging
motion and why it doesn’t continue
moving forever some of the motion is
transferred through the lines up into
the frame into the base onto the
workbench and it’s lost there a little
bit of the energy has actually turned
into heat as the billiard balls collide
with each other in a truly perfect
system the three billiard balls in the
middle would never move and the two on
the outsides would keep bouncing back
and forth forever that would also
require there is no air resistance the
little desktop toys usually use a
metallic ball which is
even better at transferring energy than
these billiard balls they’re also often
slightly magnetic which helps hold them
together if the energy from a swinging
ball isn’t pushing it out of line you
can make some really interesting
patterns by playing with this thing if
the line is swinging and then one ball
is pulled away and allowed to drop the
line will keep swinging but the outside
balls will bounce on and off random fact
the name Newton’s Cradle was coined in
1967 by the English actor Simon Preble
[Music]
by shortening the strings we eliminate
some of the play so it should last a
little bit better but we also have a
much shorter period which is the length
of time it takes the ball to swing from
one apogee to the other Newton’s Cradle
a fun toy to build and use I like trying
to figure out interesting new bounce
patterns with it overall I really enjoy
building it and it’s a good example of
Newton’s laws of motion and physics are
there other things you would like to see
us build demonstrating basic science
principles let us know down in the
comments as always if we use your idea
to make a video we will send you 25
bucks the fun’s not over that box of the
top will transport you directly to our
last video and you should check that out
the other box will show you what YouTube
thinks you need to be watching next and
if you aren’t subscribed to our channel
hit this bomb in the middle and that way
you never miss out on the fun don’t
forget to ring that Bell and we will see you in the next one talk to you then
Please follow and like us: