0:00:06 > 0:00:08# If you've got a question and you don't know where to go
0:00:08 > 0:00:11# Ask Nina for some help Cos she's got a science show
0:00:11 > 0:00:14# She makes sense of her senses While helping all her fans
0:00:14 > 0:00:17# By doing her experiments with potions and with bangs
0:00:17 > 0:00:19# Touch your tongue (Tongue)
0:00:19 > 0:00:21# Fingers (Fingers)
0:00:21 > 0:00:22# Eyes (Eyes) Ears (Ears)
0:00:22 > 0:00:24# Nose (Nose)
0:00:24 > 0:00:27# Nina and the Neurons find out what you need to know
0:00:27 > 0:00:29# Nina and the Neurons find out what you need to know
0:00:29 > 0:00:33# Luke he helps us with our eyes and Felix with our touch
0:00:33 > 0:00:36# Ollie sniffs out smells and scents and Belle she hears so much
0:00:36 > 0:00:38# Bud is Ollie's brother he helps us with our taste
0:00:38 > 0:00:41# They're Nina's little Neurons and they're coming to your place
0:00:41 > 0:00:43# Touch your tongue (Tongue)
0:00:43 > 0:00:44# Fingers (Fingers)
0:00:44 > 0:00:46# Eyes (Eyes) Ears (Ears)
0:00:46 > 0:00:48# Nose (Nose)
0:00:48 > 0:00:50# Nina and the Neurons find out what you need to know (Yeah!)
0:00:50 > 0:00:53# Nina and the Neurons find out what you need to know
0:00:53 > 0:00:55# Oh, yeah! #
0:00:56 > 0:00:59Oh, come on, Nina, come on.
0:01:01 > 0:01:03Oh, I nearly clocked one.
0:01:03 > 0:01:05Oh, hello there.
0:01:05 > 0:01:09I was concentrating so hard I didn't see you there.
0:01:09 > 0:01:10There we go.
0:01:10 > 0:01:14I'm trying to see how many blocks I can remove from this tower
0:01:14 > 0:01:16without it falling over.
0:01:16 > 0:01:18And I'm doing really well. Er, this one.
0:01:18 > 0:01:20Let's try this one. Oh.
0:01:22 > 0:01:23Oh, no!
0:01:23 > 0:01:25NINA LAUGHS
0:01:25 > 0:01:28- Hm. - ALARM BEEPS
0:01:28 > 0:01:32I hear a beep. I see a flash. I wonder what they are going to ask?
0:01:36 > 0:01:39- ALL: Hi, Nina. - Hi.
0:01:39 > 0:01:41We've got a question for you.
0:01:41 > 0:01:45- How are old buildings knocked down? - Oh, that's a great question.
0:01:45 > 0:01:48How are old buildings knocked down.
0:01:48 > 0:01:51Well, old buildings sometimes have to be knocked down
0:01:51 > 0:01:53to make space for new buildings.
0:01:53 > 0:01:58So why did you come down to my workshop and we'll investigate?
0:01:58 > 0:02:00- ALL: See you soon, Nina. Bye. - Bye.
0:02:00 > 0:02:04Well, I'm going to need some help to answer this one
0:02:04 > 0:02:05and I know just who to ask.
0:02:05 > 0:02:08OK, Neurons, time to get to work.
0:02:24 > 0:02:27ALL: Neurons at the ready, Nina.
0:02:27 > 0:02:31OK. Today's question is, "How are old buildings knocked down?"
0:02:31 > 0:02:33Which Neuron you think will be most useful
0:02:33 > 0:02:36in helping us find the answer?
0:02:36 > 0:02:38It's Belle.
0:02:38 > 0:02:43Go, Belle. Go, Belle. Go, Belle. Go, Belle. Go, Belle. Go, Belle.
0:02:45 > 0:02:49Brilliant. I'm all ears, Nina.
0:02:49 > 0:02:52Today's question is, "How are old buildings knocked down?"
0:02:52 > 0:02:56Well, knocking down buildings is a very noisy business.
0:02:56 > 0:02:59So Belle will be helping us today. But stand by, Neurons.
0:02:59 > 0:03:02I've a feeling I may need help from all of you.
0:03:02 > 0:03:04Right, I need to get the workshop ready
0:03:04 > 0:03:07before the experimenters arrive.
0:03:07 > 0:03:09Soham loves superheroes.
0:03:09 > 0:03:12Andrea likes doing puzzles.
0:03:12 > 0:03:14Yusuf loves reading.
0:03:14 > 0:03:18But they all want to know how are old buildings knocked down?
0:03:18 > 0:03:20So today, for one day only,
0:03:20 > 0:03:24Soham, Andrea and Yusuf become the Experimenters!
0:03:29 > 0:03:31- Hi, guys.- ALL: Hi, Nina.
0:03:31 > 0:03:35Welcome to my workshop and thank you for your great question,
0:03:35 > 0:03:37"How are old buildings knocked down?"
0:03:37 > 0:03:40Let's start by having a look at this.
0:03:40 > 0:03:44Sometimes old buildings are knocked down because they become unsafe
0:03:44 > 0:03:46or to make space for new ones
0:03:46 > 0:03:49and when buildings are knocked down it's called a demolition.
0:03:49 > 0:03:56Demolition. De-mo-lit-ion. Ooh, I like that word.
0:03:56 > 0:03:59So, what did you think, experimenters?
0:03:59 > 0:04:01It was loud and really quick.
0:04:01 > 0:04:04Yes, these buildings were demolished using a big bang
0:04:04 > 0:04:07that scientists call an explosion.
0:04:07 > 0:04:09Just what is an explosion?
0:04:09 > 0:04:12Let's do an experiment to find.
0:04:12 > 0:04:14ALL: Whoo-whoo! An experiment.
0:04:14 > 0:04:16We're ready, Nina.
0:04:16 > 0:04:20We are going to create our very own mini explosion
0:04:20 > 0:04:23by making these bags go pop.
0:04:24 > 0:04:27I can smell vinegar, Nina.
0:04:27 > 0:04:29So, our bag have vinegar inside them
0:04:29 > 0:04:33and these paper towels have bicarbonate of soda inside.
0:04:33 > 0:04:36We can do this because it's perfectly safe
0:04:36 > 0:04:39but you must never take things from the kitchen
0:04:39 > 0:04:41without asking a grown-up first.
0:04:41 > 0:04:44OK, so we will be putting the paper towels inside the bag,
0:04:44 > 0:04:48then sealing them up and then we'll see what happens.
0:04:48 > 0:04:50- Are you ready?- ALL: Yeah.
0:04:50 > 0:04:51Go.
0:04:57 > 0:04:59And just sit it inside gently.
0:04:59 > 0:05:04OK, now, we are going to pick up our bags and slosh them around.
0:05:04 > 0:05:05That's it.
0:05:06 > 0:05:10Andrea, put it down and take a step back.
0:05:10 > 0:05:11That's good.
0:05:11 > 0:05:15And put yours down as well, take a step back.
0:05:15 > 0:05:18So what is happening, experimenters?
0:05:18 > 0:05:20The bags are getting bigger, Nina.
0:05:20 > 0:05:24Yes, when the bicarbonate of soda and vinegar mix together,
0:05:24 > 0:05:26they react to make a gas.
0:05:26 > 0:05:28Nina. Nina?
0:05:28 > 0:05:31You can't see the gas but it's trapped inside the sealed bags
0:05:31 > 0:05:35and it is blowing them up, making them bigger and bigger.
0:05:35 > 0:05:36Nina.
0:05:36 > 0:05:39It looks like those bags are going to...
0:05:39 > 0:05:41BANG
0:05:41 > 0:05:43Pop!
0:05:43 > 0:05:44So what happened?
0:05:44 > 0:05:46The bags popped, Nina.
0:05:46 > 0:05:49Yes, when the bicarbonate of soda and vinegar mixed together,
0:05:49 > 0:05:52it made lots of gas and eventually,
0:05:52 > 0:05:55the bags couldn't hold it in any more and they...
0:05:55 > 0:05:56- ALL:- Popped!
0:05:56 > 0:06:00Yes, they popped, like a mini explosion.
0:06:00 > 0:06:03But, did this happen slowly or quickly?
0:06:03 > 0:06:04- ALL:- Slowly.
0:06:04 > 0:06:07Slowly, that's absolutely right.
0:06:07 > 0:06:11An explosion happens when gas suddenly takes up more space
0:06:11 > 0:06:15and the faster this happens, the more powerful the explosion.
0:06:15 > 0:06:18And to demolish a building, you need a really big explosion
0:06:18 > 0:06:21so you need to make lots of gas and really quickly.
0:06:21 > 0:06:25It's really important to know where the buildings will fall
0:06:25 > 0:06:28so that there's nothing in the way that could get damaged.
0:06:28 > 0:06:30But how do they know, Nina?
0:06:30 > 0:06:32That's a great question.
0:06:32 > 0:06:36I think we need to do another experiment to find out.
0:06:37 > 0:06:40We are going to pretend that this tower
0:06:40 > 0:06:43is a building that we are going to demolish
0:06:43 > 0:06:47and these blocks are other buildings and the blue material is a river.
0:06:47 > 0:06:50If we are going to knock this tower over,
0:06:50 > 0:06:52what do you think we need to avoid?
0:06:52 > 0:06:54- Other buildings.- The river.
0:06:54 > 0:06:58That's right, so we need to control what way this tower falls
0:06:58 > 0:07:01so we don't hit the other buildings and the river.
0:07:01 > 0:07:04Where do you think will be a good place for it to fall?
0:07:04 > 0:07:06The gap, Nina.
0:07:06 > 0:07:08Yes, that's right.
0:07:08 > 0:07:11How can we get the tower to fall safely into that gap?
0:07:11 > 0:07:15- Take the cans from one side, Nina. - Excellent, idea,
0:07:15 > 0:07:18and we just happen to have pieces of string here.
0:07:18 > 0:07:22I've got one each and they are attached to cans
0:07:22 > 0:07:24at the bottom of our tower on one side.
0:07:24 > 0:07:28We are going to pull these pieces of string really fast...
0:07:28 > 0:07:29NINA GIGGLES
0:07:29 > 0:07:32..as if we're removing the cans with an explosion.
0:07:32 > 0:07:36So let's pick up our pieces of string, really gently.
0:07:36 > 0:07:39- Is everyone ready? - ALL:- Yes.
0:07:39 > 0:07:42Three, two, one -
0:07:42 > 0:07:43Pull!
0:07:45 > 0:07:48THEY CHEER AND LAUGH
0:07:48 > 0:07:50- That was cool.- Oh, brilliant.
0:07:50 > 0:07:53THE NEURONS CONGRATULATE THEM
0:07:53 > 0:07:56Well done, guys, our tower fell in one direction
0:07:56 > 0:07:59and it landed exactly where we wanted it to -
0:07:59 > 0:08:01between the buildings and the river.
0:08:01 > 0:08:05And this is exactly what demolition engineers do.
0:08:05 > 0:08:07By placing explosives in just the right place,
0:08:07 > 0:08:10they can control what way the building will fall.
0:08:10 > 0:08:14Well, I must say, Nina, I'm most impressed.
0:08:14 > 0:08:16Oh, thanks, Felix.
0:08:16 > 0:08:20But, there is another way that buildings can be demolished.
0:08:20 > 0:08:24In fact, experimenters, I think it is time to get your claws out.
0:08:31 > 0:08:34Mmm, where do you think we are going today?
0:08:34 > 0:08:36Nina mentioned getting our claws ready.
0:08:36 > 0:08:39Maybe it is a zoo with lions and tigers?
0:08:39 > 0:08:42- Aah! I love lions. - HE ROARS
0:08:44 > 0:08:48Well, something is roaring but I don't think it's a lion.
0:08:48 > 0:08:53So, your question was, how are old buildings knocked down?
0:08:53 > 0:08:57So I have brought you to see this old building being demolished.
0:08:57 > 0:09:02Now, we've got special permission to be here but demolition sites
0:09:02 > 0:09:05can be really dangerous so you should never go near one.
0:09:05 > 0:09:08Now, as we found out, explosives aren't always
0:09:08 > 0:09:10the best way to demolish a building.
0:09:10 > 0:09:14- And why do you think that is? - Because of the buildings nearby.
0:09:14 > 0:09:19That's right. If there are buildings nearby.
0:09:19 > 0:09:23So another way is to use one of these special machines.
0:09:23 > 0:09:26What do you notice about the machine they're using?
0:09:26 > 0:09:28It's huge, Nina.
0:09:28 > 0:09:29It's very noisy.
0:09:29 > 0:09:32It is very noisy.
0:09:32 > 0:09:36Now, this machine is called a high reach machine,
0:09:36 > 0:09:40and its long arm reaches right to the top of the building.
0:09:40 > 0:09:45High reach machine. What a great name.
0:09:45 > 0:09:48It demolishes the building bit by bit,
0:09:48 > 0:09:51slowly working down from the top to the bottom.
0:09:51 > 0:09:55Its long arm has a big metal claw on the end and it munches
0:09:55 > 0:09:58its way through the concrete and the brick to remove them.
0:09:58 > 0:10:02A claw! Oh, that is so cool.
0:10:02 > 0:10:06Shall we have a go at doing some demolishing of our own?
0:10:06 > 0:10:07ALL: Yeah!
0:10:09 > 0:10:13We're going to pretend we're high reaching machines and these
0:10:13 > 0:10:18special grabbers are like the long arm with the claw at the end,
0:10:18 > 0:10:21and we're going to use them to demolish this cool tower.
0:10:21 > 0:10:24So where do you think we should start first?
0:10:24 > 0:10:26From the top.
0:10:26 > 0:10:29Yes. It's safest to grab the cans at the top first
0:10:29 > 0:10:31and then work our way down.
0:10:31 > 0:10:36And, remember, we don't want to hit any of these buildings nearby. OK?
0:10:36 > 0:10:38So, ready, steady,
0:10:38 > 0:10:40let's get demolishing!
0:10:46 > 0:10:48- Oh, well done.- I got one.
0:10:48 > 0:10:51Careful now. Slowly.
0:10:51 > 0:10:52Marvellous.
0:10:55 > 0:10:56Oh, that's it.
0:11:02 > 0:11:04Pull, pull, pull.
0:11:06 > 0:11:07I'll get this one.
0:11:09 > 0:11:11Oh, oh, oh, hey!
0:11:11 > 0:11:14Brilliant, demolition experimenters.
0:11:14 > 0:11:16By using the long arm and the claw,
0:11:16 > 0:11:20slowly, we have demolished the whole tower safely.
0:11:20 > 0:11:23What happened to the pieces, Nina?
0:11:23 > 0:11:25That's a great question, Andrea.
0:11:25 > 0:11:27In a real demolition,
0:11:27 > 0:11:32some pieces from an old building will be used to make new buildings.
0:11:32 > 0:11:34Excellent recycling.
0:11:39 > 0:11:42So, your question was how are old buildings knocked down?
0:11:42 > 0:11:44And I think we've answered it.
0:11:44 > 0:11:49When an old building is taken down, it's called the demolition.
0:11:49 > 0:11:52Engineers put explosives in the bricks and concrete
0:11:52 > 0:11:53to blow them apart.
0:11:53 > 0:11:57The explosion happens when gas suddenly takes up more space.
0:11:57 > 0:11:59They place explosives carefully
0:11:59 > 0:12:02to control which way the building will fall.
0:12:02 > 0:12:07Buildings are also demolished using high reach machines.
0:12:07 > 0:12:10So, I hope that's answered your question.
0:12:10 > 0:12:12ALL: Thanks, Nina. Bye!
0:12:12 > 0:12:16You're welcome. Bye!
0:12:17 > 0:12:21If you want to know more about the science that is all around us,
0:12:21 > 0:12:24go to the Nina section on the CBeebies website. Have fun!
0:12:24 > 0:12:26# Superstructures
0:12:26 > 0:12:28# Superstructures
0:12:28 > 0:12:32# Superstructures, superstructures superstructures!
0:12:32 > 0:12:34# Some of them are tall
0:12:34 > 0:12:36# Some of them are wide
0:12:36 > 0:12:38# They're bumpy, lumpy, wiggly, too
0:12:38 > 0:12:40# Wiggly, too
0:12:40 > 0:12:42# Some of them are strong
0:12:42 > 0:12:44- # Some of them are small... # - Like me!
0:12:44 > 0:12:47# They're windy, whirly whooshy, too
0:12:47 > 0:12:48# All around
0:12:48 > 0:12:50# Look over here
0:12:50 > 0:12:52# Build it, stack it
0:12:52 > 0:12:54# Pile it up
0:12:54 > 0:12:56# Come on, let's get building... #
0:12:56 > 0:12:58Building! Building! Building!
0:12:58 > 0:13:00# Brace it, hold it
0:13:00 > 0:13:02# Make it stick
0:13:02 > 0:13:05# Come on, let's get building
0:13:05 > 0:13:06# Whee-oo-ooh
0:13:06 > 0:13:09# Come on, let's get building
0:13:12 > 0:13:14# Some of them are cosy warm
0:13:14 > 0:13:16- # Some of them are chilly... # - Brrr!
0:13:16 > 0:13:18# Keep us safe and hide us, too
0:13:18 > 0:13:20# Hide us, too!
0:13:20 > 0:13:22# Some of them are just for fun
0:13:22 > 0:13:24# Or help us to stay dry
0:13:24 > 0:13:27# They're underground and high up, too
0:13:27 > 0:13:28# Look around
0:13:28 > 0:13:30# Over here
0:13:30 > 0:13:33# Build it, stack it
0:13:33 > 0:13:34# Pile it up
0:13:34 > 0:13:37# Come on, let's get building... #
0:13:37 > 0:13:39- Building!- Building!- Building!
0:13:39 > 0:13:40# Brace it, hold it
0:13:40 > 0:13:42# Make it stick
0:13:42 > 0:13:45# Come on, let's get building
0:13:45 > 0:13:46# Whee-oo-ooh
0:13:46 > 0:13:49# Come on, let's get building! #
0:13:50 > 0:13:54And, remember, there are superstructures everywhere.
0:13:54 > 0:13:57Whether they're big or small, wide or tall,
0:13:57 > 0:13:58we can all get building.
0:13:58 > 0:14:00See you again soon. Bye!
0:14:00 > 0:14:02ALL: Bye!