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00:30there's only one way off
00:35hello and welcome once again
00:39to think of a number
00:40I've learnt to ride it but I haven't learnt to get off
00:43penny farthing bicycle
00:45now
00:46what number is that
00:48I'm a one and there's two noughts
00:51so it's
00:51a hundred
00:54absolutely
00:54which is remarkable
00:55because it was a hundred years ago
00:57that people
00:57the fools
00:58were riding around
00:59or something like this.
01:01But it was 100 years ago that lots of other things started happening.
01:05Have a look at this.
01:151876. Alexander Graham Bell invented the telephone.
01:201877. Thomas Edison made a very scratchy recording of
01:23Mary Had a Little Lamb on the world's very first gramophone.
01:27It doesn't look as though he was very happy with the results.
01:331878. The very first filament bulb which was made by Joseph Swan
01:39in Newcastle-on-Tyne.
01:41But for that, we'd all be watching television by gaslight.
01:451880. The first gents' wristwatch with the face on the wrong way round.
01:491882. The first electric iron.
01:52And 1884. The very first fountain pen.
01:541880. And Carl Benz invented the very first petrol-driven motor car.
02:01And that really got things moving.
02:04So, costume.
02:18There we are.
02:20We're just about dressed because we're going to take you back about 100 years.
02:23Not to an inventor's workshop,
02:26but to a normal Victorian parlour.
02:28But in Victorian times, they like to entertain each other rather like this.
02:42Gather round, ladies and gentlemen,
02:44because I have here some coins of the realm
02:46which I shall place on my right elbow thusly.
02:49The object to transfer the coins to my right hand
02:52without the aid of my left arm.
02:54How can I accomplish this feat?
02:56As simple as that.
02:58I shall now proceed with my next trick.
03:01Six glasses of a rather pale vintage of wine
03:04supporting a piece of glass
03:06and some cardboard tubes
03:07and six eggs,
03:09the fruit of the farmyard hen.
03:11Now, the object to remove the glass
03:13and drop the eggs into the glasses.
03:16So, thank you very much.
03:20Pausing to address just this shirt,
03:22I shall perform the next trick.
03:24To remove this tablecloth
03:25while leaving mother's best derby china
03:28absolutely intact and unimparted.
03:33So, and now,
03:35I shall proceed to my final trick.
03:40A broom handle
03:41supported by two needles
03:43on two wine glasses
03:45and I am now
03:46going to sever the broom
03:47in the middle
03:48without damaging the wine glasses
03:50in any way.
03:52So,
03:53now,
04:03why did those tricks work?
04:07Well, to be honest,
04:09we cracked this glass here.
04:10You see?
04:11But it nearly worked.
04:14And the reason it works,
04:16if you do it right,
04:17I must have held back with the sword,
04:18is this.
04:19When the sword comes down,
04:20the force is acting in this direction
04:22very quickly,
04:23starting the middle of the broom
04:25down in the same direction
04:27very quickly.
04:28And that force
04:29happens so quickly
04:30that no force
04:31travels
04:32to the end of the broom.
04:34Well, not enough
04:34because the broom
04:36breaks before any force
04:37reaches the glasses.
04:38So, usually,
04:40they're undamaged.
04:42A similar thing
04:43makes this trick work here.
04:46The cups and saucers
04:46are held down
04:47by their weight
04:48and gravity
04:49on the table.
04:50They're held down
04:51with a force
04:51in that direction.
04:52You see,
04:53it's all to do
04:53with Isaac Newton's
04:55first law
04:55of movement
04:56or motion,
04:58which says
04:58that objects
04:59that are stationary
05:00like to stay stationary.
05:03And objects
05:04that are moving
05:05like to keep moving.
05:07Over here,
05:08we've got some trolleys.
05:09Can you bring your trolleys
05:10out here?
05:10Move that over there.
05:13And over here,
05:14shift that.
05:15Over here,
05:15we've got a sort of
05:16silver starting line.
05:17Put your trolleys
05:18on the line
05:18so that the elastic
05:19is facing this way
05:20and then just,
05:22that's right,
05:22and just stretch
05:23your elastic out
05:24in a long line
05:25that way.
05:28Very good.
05:30Just so that
05:31it's straight out.
05:32Fine.
05:33I'm going to give you
05:33a passenger person.
05:35Little rockers
05:36here.
05:38I don't know
05:38the punk rockers
05:39they haven't got earrings,
05:39have they?
05:40Never mind.
05:41Right, now,
05:42just put one turn
05:43around your finger.
05:44That's lovely.
05:45That's fine.
05:45So you don't let go.
05:46Hold your hands
05:47quite near the floor.
05:49And what I want you to do,
05:51when I say go,
05:52I want the three of you
05:53to start going back
05:53in a line
05:54so that you stretch
05:55your elastic
05:56and pull.
05:58Now you keep pulling
05:59nice and gradually.
06:01That one's going.
06:02Don't pull anymore.
06:04Now you keep pulling
06:05nice and gradually.
06:06that's it.
06:11Stop there.
06:13Because that proves
06:14or shows
06:16Isaac Newton's
06:17second law of motion,
06:18which says
06:19that the bigger
06:20or heavier a thing is,
06:22the bigger the mass,
06:24the more force
06:25needed to move it.
06:26and that's why
06:26you had to stretch
06:27your elastic much more
06:28to move this one
06:29than the other two did.
06:30Right?
06:31I'll show you
06:31something else.
06:36I want you to do it again.
06:38Just you.
06:38And this time,
06:39I want you to do it
06:40quite vigorously.
06:42So back at about this speed.
06:45OK?
06:46And keep going
06:46until it's moving.
06:47Right?
06:48Ready?
06:48Go.
06:49Nice and vigorously.
06:50And watch the model.
06:50Watch the man.
06:52Off it goes.
06:53See what happens?
06:54It rocks backwards.
06:54That's enough.
06:55Now watch this.
06:58I stopped him
06:58and he rocked forward.
07:00Thanks very much.
07:01That was lovely.
07:01Thanks for helping.
07:02Talk.
07:03APPLAUSE
07:04There we are.
07:09Things that are moving
07:11like to keep moving.
07:14But if things that are moving
07:15like to keep moving,
07:17how do you explain this?
07:28It's stopped.
07:29And it always stops.
07:31Now why is that?
07:33Well the reason is,
07:33there's another force
07:34acting on it.
07:35A force called friction.
07:38And it's friction
07:39between the wheels
07:39and the ground.
07:41Between the wheels
07:41and the axle.
07:42Between the axle
07:43and the cart.
07:44And that friction
07:45slowly slows it down
07:47until it stops.
07:49And without friction,
07:50as I start walking now,
07:53without friction
07:53I wouldn't be able to stop.
07:55My feet
07:55wouldn't grip the floor.
07:57And I'd slide
07:58as I was on ice.
07:59And I'd keep moving
08:00until I got to the other end
08:02of the studio
08:02and I'd hit the wall.
08:03Boing!
08:04And then I'd bounce off it
08:05and come back this way
08:07and hit that wall
08:07and keep going.
08:09So only friction
08:10stops me.
08:11I can show you friction
08:12with a stick.
08:14You've all got sticks
08:14over here, haven't you?
08:15I want you to hold a stick
08:16on your fingers
08:17like that.
08:19Right?
08:21Just let it rest
08:22and now move
08:23your left finger
08:24into the centre.
08:30Don't move your right,
08:31just move your left.
08:33Can't you do it?
08:34You can cheat
08:35by holding one end.
08:36That's easy.
08:37Or if you do it quickly,
08:38you can sort of get there.
08:40But if you do it slowly,
08:41you can't do it.
08:44Anybody done it?
08:46What happens is this.
08:47When you've got the stick
08:47on your fingers,
08:48the weight is evenly distributed
08:50between the two.
08:51And so,
08:52the friction between each finger
08:53and the stick
08:54is the same.
08:55And when you start moving
08:56one finger,
08:58as it gets near the centre,
09:00it takes more weight.
09:01So there's more friction.
09:03So there's less friction
09:04on the other finger.
09:05and that then
09:06starts to move.
09:08And when the thing's
09:09evened out,
09:10or this is taking
09:11more friction,
09:12the other finger
09:12starts to move.
09:15And the two fingers
09:16always finish up
09:16together in the middle.
09:19Now, if you can overcome
09:20inertia and friction,
09:22you can move anything,
09:25even something
09:25like this.
09:26Does anybody know
09:39what it is?
09:41What's that?
09:42Cleopatra's Needle.
09:43Cleopatra's Needle.
09:44That's right.
09:44It stands on the embankment
09:46at the Thames,
09:47of the Thames,
09:47in London,
09:48and it stood there
09:49for just over 100 years.
09:51But it's much older
09:52than that,
09:523,400 years old.
09:55It weighs
09:57186 tonnes
09:59and it's 62 and a half feet
10:01at 20 metres tall.
10:04And it's actually
10:04almost twice as old
10:05as Cleopatra herself.
10:07It was cut
10:08in one piece
10:09in a quarry
10:10in Egypt
10:12and then floated
10:13down the river
10:13to the mouth
10:14of the Nile
10:14where it was erected
10:16and it stood
10:16for about 3,000 years.
10:19100 years ago,
10:20a special ship
10:21was built
10:22and it was put inside
10:24and towed
10:25through very stormy seas
10:26back to England.
10:28And then
10:29they started
10:31to erect it.
10:33They built the platform
10:34and slowly winched it up
10:35with four
10:35great hydraulic jacks
10:37building a scaffold
10:38underneath it
10:39as it went.
10:41When they got it
10:41to the top,
10:42they tied horses
10:43and wires to it
10:44and pulleys
10:45and slowly tilted it
10:46and lowered it
10:49into place.
10:50And the crowds
10:51cheered
10:52as the Victorians
10:53had used all their
10:54ingenuity
10:54to place it there.
10:57But if it had taken
10:58the Victorians
10:59so much trouble,
11:00how did the Egyptians
11:01manage it
11:023,000 years ago?
11:04Well, they must have known
11:05about something called
11:06mechanical advantage.
11:08Ah, just unhook this.
11:22Here we are.
11:23Some swings.
11:24Now, have we got
11:24a strong lad?
11:25Can you come out here,
11:26please?
11:27And, er,
11:28can you come out?
11:31Come over here.
11:32Your name is?
11:33Martin.
11:33Martin.
11:34OK, Martin.
11:35And you're?
11:35Stephen.
11:36Stephen.
11:36Right-o.
11:37Martin, do you reckon
11:38you can lift Stephen?
11:40Stephen, come over here.
11:41I want you to sit
11:42on this swing.
11:43You have to put
11:43one leg through.
11:46OK?
11:46And sort of sit
11:47astride it,
11:48rather like on the end
11:49of a seesaw,
11:50and hold the rope.
11:50OK.
11:51Now, if you pull this,
11:52see if you can lift him up.
11:56Well, you're lifting him.
11:57Can you lift him any higher?
11:59You're doing it.
12:00But what's happening?
12:02It's nearly lifting you,
12:03isn't it?
12:04Do you think you could lift,
12:05er,
12:05two people?
12:06You doubt it.
12:09Well, you get on that one,
12:09and we'll get somebody else.
12:12Er,
12:13can you come and help?
12:15Can you hutch up a bit?
12:17Put your leg through there.
12:19That's it.
12:20And hang on to the ropes.
12:22And Martin,
12:23you take this rope,
12:25and see if you can lift them.
12:30It seems easier
12:31than the last load,
12:32is it?
12:32Can you hold it there for a second?
12:34We'll see how it works.
12:35The rope goes over that pulley,
12:37down under this one,
12:38over that one again,
12:39and then fastens on to this pulley.
12:42If you count the ropes there,
12:43they're one,
12:43two,
12:43three,
12:44and one here.
12:45What you've got
12:46is a three-to-one
12:47mechanical advantage.
12:49Now,
12:49you've lost some of that
12:50through the friction
12:51with the pulleys.
12:52But you've been able
12:52to lift twice the load
12:54you could
12:54with just a simple pulley.
12:56Okay.
12:57Right,
12:57let them go.
12:58Do you think you could lift,
12:59um,
13:00three?
13:03Okay,
13:04we'll put them on there.
13:04We'll try it with four
13:05if you like.
13:07Both of you get on there.
13:08And can I have two more?
13:09Two girls, I think.
13:10Do you want to come and help?
13:11Go on.
13:12It's all right.
13:13You might be able to get in there.
13:14Do you want to come and help?
13:17Perhaps you can just sit
13:18on the end facing that way.
13:19Okay.
13:20Hang on to the ropes.
13:21Let's see if you can lift this.
13:24You didn't know you'd be working
13:25for me today, did you?
13:26Right.
13:28Lift.
13:30Oh,
13:30that's just about
13:31as much as you can take,
13:32isn't it?
13:33That's incredible.
13:34That's four people you've lifted.
13:35Let me help you.
13:36If we count the ropes this time,
13:38one,
13:38two,
13:39three,
13:39four,
13:39five,
13:40six to one.
13:41You've got a mechanical advantage
13:42of six to one.
13:43But you've got to pull the rope
13:44yards
13:45to lift them just
13:46a few inches,
13:48haven't you?
13:48Okay,
13:49shall we let them go?
13:50Look out!
13:50Thanks very much.
13:53Give them a big hand
13:53for swinging around.
13:57So, just as mechanical advantage
14:02can be used
14:03for pulling,
14:04so mechanical advantage
14:06can be used
14:06for pushing.
14:07how can I move this brick?
14:11Oh,
14:11I've moved it.
14:12No,
14:13what I mean is this.
14:14Can I blow it
14:15and move it?
14:20Of course,
14:21I can't.
14:21But if I blow it
14:22to a balloon,
14:24I'll just see what happens.
14:25try again.
14:38It's moved it.
14:39See,
14:40when you blow up
14:40a balloon,
14:42the pressure
14:45inside the balloon
14:46is having an equal force
14:48on the whole surface
14:49of the balloon.
14:49So the more balloon
14:51there is touching the brick,
14:52the more force applied.
14:54So the brick moves.
14:56And that's how
14:57hydraulic jacks work.
14:59Now,
14:59hydraulic jacks,
15:00four of them,
15:01lifted
15:01Cleopatra's needle.
15:03But modern
15:04hydraulic jacks
15:05can move
15:05immense loads.
15:07They can move things
15:07as big as this.
15:08This is a jacket.
15:18It's a bit short
15:19on the sleeve.
15:20Actually,
15:21it's called a jacket,
15:22but you know what it is?
15:23It's the legs
15:24for an oil platform.
15:26And it's the biggest one
15:28that's been built
15:28and launched
15:29from a barge.
15:30Weighs 25,000 tonnes.
15:35Now,
15:35it's been built
15:36on the land
15:37and it's been moved
15:38onto the barge.
15:38here.
15:39But how?
15:41No wheels,
15:42no rollers.
15:43If you put this weight
15:44on wheels
15:45and started it moving,
15:46you never stop it.
15:48It's just being dragged
15:49or pushed
15:50along these
15:51two skid tracks.
15:55And it's being pushed
15:56by just two
15:56hydraulic jacks.
15:58But they've got
15:58a mechanical advantage,
16:00not of
16:00three to one
16:01or six to one,
16:02of about 700 to one.
16:04And there are two of them.
16:06Now,
16:06if you try to push
16:0825,000 tonnes,
16:10what happens?
16:12It pushes you,
16:13doesn't it?
16:14So you need to grip,
16:16get a firm footing.
16:17And that's what
16:18these hydraulic jacks
16:19need to do.
16:19and they do this
16:21like this.
16:30The balloon,
16:31the pressure in the balloon
16:31is pushing the balloon
16:32against the glass
16:33and it doesn't matter
16:34how much I pull,
16:35it won't come out.
16:37Well,
16:38it's stretching
16:39but it's not coming out.
16:41That's because
16:42there's friction
16:44set up by the pressure
16:45between the,
16:45friction between the balloon
16:47and the glass.
16:49And that's how
16:50these hydraulic jacks work.
16:51They clamp on
16:52to the skid rail
16:53like that.
16:55And the space in between
16:56is filled with
16:57hydraulic hoses
16:58which are pumped up,
16:59pumped so hard
17:01that the friction
17:02caused
17:03is greater
17:04than the friction
17:05caused by
17:0625,000 tonnes
17:07resting
17:08on these skid tracks.
17:10So when they push
17:11it's this
17:12massive construction
17:14that moves.
17:16Now,
17:17just a couple of months ago
17:18this whole thing
17:20was pushed
17:21onto the barge
17:22and floated out
17:22into the North Sea.
17:25And then
17:26it was pushed
17:26off the barge
17:27it was submerged
17:29tilted
17:30and located
17:31by satellite.
17:32so it dropped
17:33to the bottom
17:34of the sea
17:34at exactly
17:36the right spot.
17:37So there was
17:38just a fraction
17:39of it
17:39peeping out
17:41at the top
17:41of the sea.
17:42And on top
17:43of that
17:43they're going
17:44to build
17:44this.
17:46This.
18:02is this.
18:21This is called the topside facility for an oil production platform.
18:36It's the bit you see above the sea.
18:38There's the sea level there.
18:41And just to give you some idea of how deep the sea is and what it's like,
18:46I get a model.
18:48This is a model of the post office tower.
18:52Well, it's only the top of it, that's the amount that would stick out of the water
18:57if it had been sunk in the same depth.
19:00512 feet of water.
19:02And that's the post office tower.
19:04So you've got this at an incredible height.
19:07But it's massive.
19:08The top area is just fractionally smaller than the Wembley playing pitch.
19:16And have a look at everything.
19:17There's lifeboats here.
19:19I think they'd need those, don't you?
19:20There's a helipad up here for helicopters because it's 150 miles from land.
19:26They live in this block here, which runs the whole width of the rig.
19:29It's three storeys high.
19:31And it's like a hotel for 198 men.
19:36But the business end is here.
19:38This is the gantry.
19:39Have a look at that.
19:42It's enormous.
19:43This is a model of Nelson's column, isn't it?
19:55It's built to the same scale as this rig.
19:59But if you look at it, and look at the derrick, you find they're about the same size.
20:05So what you've got is the post office tower, on top of which is something which is the size of Wembley playing pitch.
20:15On top of which is Nelson's column.
20:20But that bit that's like Nelson's column is capable of being dragged from that end to this end here.
20:28By two hydraulic jacks.
20:30And it's also capable of being moved across from there to here by two more hydraulic jacks.
20:38Why does it need to be moved?
20:41Well it's not going to drill one hole.
20:43It's going to drill 22 holes.
20:4610,000 feet below the bed of the sea.
20:48Why 22?
20:51Well 10 of them are going to be used to bring the oil up.
20:56But 10 will be to inject seawater in its place.
21:00And 2 to pump gas in to force the oil out under pressure.
21:05And the whole structure is massive.
21:07It weighs 57,000 tonnes.
21:10Which is equal to about 5,000 double-decker buses.
21:13It produces enough electricity to keep the city of Edinburgh going.
21:19And all this is in one of the roughest seas in the world.
21:24150 miles north of the Shetlands.
21:26In the North Sea.
21:29And it costs 500 million pounds.
21:33Why?
21:34Well when it's in full stream it'll produce 150,000 barrels of oil a day.
21:40And every day that oil will keep going 15,000 private cars for a year.
21:48At present day prices that oil will be worth 2.5 million pounds every single day.
21:56So with the aid of the oil from the North Sea it should keep things moving.
22:02And we won't have to go back to riding penny-farlene bicycles.
22:05Let's have a trick.
22:08Who wants to do a trick?
22:09Will you have a go?
22:10Come round here.
22:11I'm going to stay around here.
22:13Okay.
22:13Pack of cards.
22:14Just take half and give me half.
22:16Either half.
22:17Doesn't matter.
22:18Those?
22:19Right.
22:19Give me a number between 1 and 10.
22:215.
22:225.
22:22Right.
22:24I'm going to turn over 5 cards.
22:25Stick them in there.
22:30Can you shuffle cards?
22:31Now!
22:32Oh.
22:33Alright.
22:34Do you think they're shuffled?
22:35Yeah.
22:35Or cut them.
22:36Let's sort of take the top half.
22:38Put it on the bottom.
22:41Hold them under the table.
22:42And I'll show you what...
22:43With both hands.
22:45I'll show you what to do.
22:46I want you to count off 5 into your other hand like that.
22:491, 2, 3, 4, 5.
22:51Okay?
22:52Give that packet to me.
22:54The 5?
22:54The 5.
22:55Thank you very much.
22:57And you can come up again now.
22:59I'm staying down here.
23:00Because I'm feeling my cards.
23:02And I can tell that I've got exactly as many face up as you've got face up.
23:07I've got 5 face up.
23:13That's incredible.
23:13How many have you got?
23:15Deal them all out.
23:15No, the other way.
23:17Deal them out quickly.
23:18None.
23:20None.
23:20None.
23:22None.
23:221, 2, 3, 4, 5.
23:31Thank goodness it worked.
23:33Thanks very much for helping.
23:34If you'd like to know how that trick's done, drop me a line.
23:40Johnny Ball, Think of a Number, BBC Television, London, W1A, 1AA.
23:46Well, that's the end of this show.
23:47It's also the end of this series of Think of a Number.
23:50But we'll be back next year with some more ideas.
23:53So until then, it's goodbye from me.
23:59Happy goodbye from me!
24:04Happy goodbye from me!
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