0:00:06 > 0:00:09# If you've got a question and you don't know where to go
0:00:09 > 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 > 0:00:30# Nina and the Neurons find out what you need to know
0:00:30 > 0:00:33# Luke, he helps us with our eyes and Felix with our touch
0:00:33 > 0:00:35# Ollie sniffs out smells and scents and Belle she hears so much
0:00:35 > 0:00:39# Bud is Ollie's brother, he helps us with our taste
0:00:39 > 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 > 0:00:45# Fingers Fingers
0:00:45 > 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 > 0:00:58Oh, come on, Nina, here we go.
0:00:58 > 0:00:59Oh, hello there.
0:00:59 > 0:01:02I'm just about to do a very cool experiment.
0:01:02 > 0:01:04Here we go.
0:01:05 > 0:01:08Oop.
0:01:08 > 0:01:11Ah!
0:01:11 > 0:01:15It's all staying up because it's perfectly balanced.
0:01:15 > 0:01:17ALARM BEEPS
0:01:17 > 0:01:21I hear a beep. I see a flash. I wonder what they are going to ask?
0:01:24 > 0:01:27- ALL: Hi, Nina. - Hi.
0:01:27 > 0:01:29We've got a question for you.
0:01:29 > 0:01:31How does a bridge work?
0:01:31 > 0:01:34Oh, that's a great question.
0:01:34 > 0:01:35How does a bridge work?
0:01:35 > 0:01:37Now, a bridge is a big structure.
0:01:37 > 0:01:41It's built over rivers so that things get across it.
0:01:41 > 0:01:45Why don't you come down to my workshop and we'll investigate?
0:01:45 > 0:01:47ALL: See you soon, Nina. Bye.
0:01:47 > 0:01:49Bye.
0:01:49 > 0:01:52Well, I'm going to need some help to answer this one
0:01:52 > 0:01:54and I know just who to ask.
0:01:54 > 0:01:56OK, Neurons, time to get to work.
0:02:12 > 0:02:14ALL: Neurons at the ready, Nina.
0:02:14 > 0:02:17OK. Today's question is, "How does a bridge work?"
0:02:17 > 0:02:21Which Neuron do you think will be most useful in helping us
0:02:21 > 0:02:23find the answer?
0:02:23 > 0:02:25It's Felix!
0:02:25 > 0:02:30Go, Felix. Go, Felix. Go, Felix. Go, Felix. Go, Felix.
0:02:33 > 0:02:37Marvellous. A little touch can mean so much, Nina.
0:02:37 > 0:02:40Today's question is, "How does a bridge work?"
0:02:40 > 0:02:42and because bridges help hold things up,
0:02:42 > 0:02:45Felix our touch Neuron will be helping us today
0:02:45 > 0:02:46but stand by, Neurons,
0:02:46 > 0:02:49I've a feeling I mean need help from all of you.
0:02:49 > 0:02:55I need to get the workshop ready before the experimenters arrive.
0:02:55 > 0:02:57Billie loves sandwiches.
0:02:57 > 0:02:59Alexander likes making up his own stories.
0:02:59 > 0:03:01Marianna loves dancing.
0:03:01 > 0:03:04But they all want to know, how does a bridge work?
0:03:04 > 0:03:06So today, for one day only,
0:03:06 > 0:03:11Billie, Alexander and Marianna become the experimenters.
0:03:17 > 0:03:19- Hi, guys. - ALL: Hi, Nina.
0:03:19 > 0:03:23Welcome to my workshop and thank you for your great question,
0:03:23 > 0:03:24how does a bridge work?
0:03:24 > 0:03:27There are lots of different types of bridges.
0:03:27 > 0:03:30Some are straight, some are arches
0:03:30 > 0:03:32and some bridges have strong cables.
0:03:32 > 0:03:34Have a look at this one.
0:03:34 > 0:03:37This is the Forth Bridge and it is a special type.
0:03:37 > 0:03:40It's called a cantilever bridge.
0:03:40 > 0:03:43- Canti... what? - A cantilever, Bud.
0:03:44 > 0:03:46It is a tricky word.
0:03:46 > 0:03:49Cantilevers are only held up at one end.
0:03:49 > 0:03:51The other end has to stay up by itself.
0:03:51 > 0:03:53How does it work, Nina?
0:03:53 > 0:03:58Oh, let's try an experiment with our very own cantilevers to find out.
0:03:58 > 0:04:03ALL: Woo-woo! An experiment. We're ready, Nina.
0:04:03 > 0:04:05So, here we have some cantilevers
0:04:05 > 0:04:09and, as you can see, they're only held up at one end.
0:04:09 > 0:04:11These have been specially made
0:04:11 > 0:04:14so you should never try something like this yourself.
0:04:14 > 0:04:17These cantilevers are all the same thickness
0:04:17 > 0:04:19but they are all different lengths.
0:04:19 > 0:04:22And I would like you guys to try standing on them
0:04:22 > 0:04:25to see if they'll hold your weight. OK.
0:04:25 > 0:04:29So, Billie, I'd like you to stand on the shortest one. Up you go.
0:04:29 > 0:04:31Good lass. Stand right at the end.
0:04:31 > 0:04:34OK, Marianna, a big step up. Good girl.
0:04:37 > 0:04:41Excellent. Now carefully walk to the end.
0:04:41 > 0:04:45So what happened? Are your cantilevers holding you up?
0:04:45 > 0:04:46My one's bending.
0:04:46 > 0:04:51Oh, yes. The longest cantilever is feeling a bit bendy.
0:04:51 > 0:04:55You're right. Your long cantilever is bending.
0:04:55 > 0:04:59So shorter cantilevers can hold up weight more easily.
0:04:59 > 0:05:02But if a cantilever is longer, it's more difficult
0:05:02 > 0:05:04for it to hold up weight.
0:05:04 > 0:05:07Well done, experimenters. Let me get you down.
0:05:07 > 0:05:10So the Forth Bridge is a cantilever bridge.
0:05:10 > 0:05:13And cantilevers are only held up at one end.
0:05:13 > 0:05:15But the longer the cantilever gets,
0:05:15 > 0:05:19the more difficult it is for it to hold something up.
0:05:19 > 0:05:21Exactly, Neurons.
0:05:21 > 0:05:24But cantilever bridges need to be really long
0:05:24 > 0:05:26to get across big rivers.
0:05:26 > 0:05:29I wonder if there is a way that we can help long cantilevers
0:05:29 > 0:05:31to stay up?
0:05:31 > 0:05:35I think we need to go on a trip to a really big river to find out more.
0:05:38 > 0:05:40Oh, goody. I love this bit.
0:05:40 > 0:05:43I wonder where Nina is taking us.
0:05:43 > 0:05:46Nina said we were going to a big river.
0:05:46 > 0:05:49Oh, oh, maybe we are going on a boat.
0:05:49 > 0:05:50Or in for a swim.
0:05:50 > 0:05:53Look, everyone. We're here.
0:05:56 > 0:06:01So I've brought you to this big river to see a very special bridge.
0:06:01 > 0:06:03Do you recognise it?
0:06:04 > 0:06:08- It's the Forth Bridge.- It is the Forth Bridge, near Edinburgh,
0:06:08 > 0:06:10and it was built a long time ago.
0:06:10 > 0:06:13ALL: Ooh! It's really long.
0:06:13 > 0:06:16Even though this bridge has long cantilevers
0:06:16 > 0:06:20it can still hold up heavy trains without bending.
0:06:20 > 0:06:25I think we need to do an experiment to find out how it works.
0:06:25 > 0:06:28We've got three cantilevers here
0:06:28 > 0:06:30and they're all the same length.
0:06:30 > 0:06:33Marianna, your one has no extra beams.
0:06:33 > 0:06:36Billie, your one has a beam underneath
0:06:36 > 0:06:39and Alexander, you have a long cantilever
0:06:39 > 0:06:42with a beam underneath and on top.
0:06:42 > 0:06:45And we also have some lovely heavy weights there.
0:06:45 > 0:06:49So let's see if the beams help the long cantilever
0:06:49 > 0:06:51to hold up more weight.
0:06:51 > 0:06:55We're going to add the weights at the same time, so are you ready?
0:06:55 > 0:06:58- ALL: Yeah. - OK, here we go.
0:06:58 > 0:07:00Pick up your first weight
0:07:00 > 0:07:04and pop it on to the end of your long cantilever.
0:07:04 > 0:07:05Oh, dear.
0:07:05 > 0:07:08That long cantilever looks bent already.
0:07:08 > 0:07:11Oh, no. What happened?
0:07:11 > 0:07:13Mine's bent.
0:07:13 > 0:07:15Yes, your long cantilever without the beams
0:07:15 > 0:07:17is already starting to bend.
0:07:17 > 0:07:20So it could only hold up one weight.
0:07:20 > 0:07:24OK, so let's see if we can add some more weight to the other two here.
0:07:24 > 0:07:27So pick up another weight for me.
0:07:27 > 0:07:30That's it. And pop it right at the end.
0:07:30 > 0:07:32OK.
0:07:32 > 0:07:34They are looking pretty good.
0:07:34 > 0:07:36Let's add another weight.
0:07:37 > 0:07:39Very good.
0:07:39 > 0:07:42OK. Pick up another weight for me. Pop it on.
0:07:44 > 0:07:46Oh, look, Billie.
0:07:46 > 0:07:48Your cantilever with the beams underneath
0:07:48 > 0:07:52is starting to bend now and that's got one, two, three,
0:07:52 > 0:07:53four weights on it.
0:07:53 > 0:07:56OK, well, Alexander, I think we could keep trying to put
0:07:56 > 0:08:00weights on your cantilever, so do you want to keep going?
0:08:00 > 0:08:04Wow. It's holding lots of weights.
0:08:04 > 0:08:06Look at that.
0:08:06 > 0:08:08There are no more weights to put on.
0:08:08 > 0:08:09You've put all six on
0:08:09 > 0:08:11and it's still not bending.
0:08:11 > 0:08:13That's fantastic.
0:08:13 > 0:08:14When a weight is added
0:08:14 > 0:08:16the cantilever is pushed down
0:08:16 > 0:08:21and the beam and underneath pushes up, which stops it from bending.
0:08:21 > 0:08:24And if there is a beam on top as well, that's even better.
0:08:24 > 0:08:27So as well as the beam underneath pushing up,
0:08:27 > 0:08:31there's a beam on top pulling up at the same time.
0:08:31 > 0:08:34And this is how a really long cantilever can hold up
0:08:34 > 0:08:36a lot of heavy weights.
0:08:36 > 0:08:40And the Forth Bridge is made like this, too.
0:08:40 > 0:08:44So the long cantilevers are joined by the towers at the end
0:08:44 > 0:08:47and there's a beam on top of the long cantilever
0:08:47 > 0:08:48that helps to pull it up
0:08:48 > 0:08:51and there's a beam underneath the cantilever
0:08:51 > 0:08:53that helps to push it up, too,
0:08:53 > 0:08:58which means that it can hold up all the heavy trains that go over it.
0:08:58 > 0:09:01So that's how they stop the long cantilever from bending?
0:09:01 > 0:09:04There's a beam on top and underneath.
0:09:04 > 0:09:08Which means it can hold up really heavy things like trains.
0:09:08 > 0:09:10Choo-choo!
0:09:10 > 0:09:12Well remembered, Neurons.
0:09:12 > 0:09:15- The bridge is really strong, Nina.- It is.
0:09:15 > 0:09:19And, actually, that reminds me of a really fun experiment
0:09:19 > 0:09:22and I'll be needing some strong helpers.
0:09:24 > 0:09:27So your question was, "How does a bridge work?"
0:09:27 > 0:09:30And so far we've discovered that adding a beam on top
0:09:30 > 0:09:34and underneath a long cantilever bridge stops it from bending.
0:09:34 > 0:09:38And that means it can hold up heavy things like trains.
0:09:38 > 0:09:41And I think we need to do one final experiment.
0:09:41 > 0:09:47Do you think we could build a human cantilever bridge using our bodies?
0:09:47 > 0:09:50- ALL: Yes. - Well, let's do it.
0:09:50 > 0:09:53Into your seats, guys. That's it, round you go.
0:09:53 > 0:09:55Now lift up those poles.
0:09:55 > 0:09:58A human cantilever bridge.
0:09:58 > 0:10:01Nina thinks of the most unusual experiments.
0:10:01 > 0:10:03But they're the most fun.
0:10:03 > 0:10:04Oh, wow.
0:10:04 > 0:10:10You've built a great bridge and it looks just like the Forth Bridge.
0:10:10 > 0:10:13So you guys are the towers' experimenters
0:10:13 > 0:10:17and you're holding up the middle sections of the bridge.
0:10:17 > 0:10:19Your arms are the top beams
0:10:19 > 0:10:22and the poles are the beams underneath
0:10:22 > 0:10:25and there's also some heavy weights at the sides
0:10:25 > 0:10:27just helping you balance.
0:10:27 > 0:10:29I think we need to put this bridge to the test.
0:10:29 > 0:10:34Do you think your lovely bridge could hold up
0:10:34 > 0:10:37these heavy trains?
0:10:37 > 0:10:39- Yes.- Well, I think we need to try.
0:10:39 > 0:10:41Here we go. Choo-choo.
0:10:43 > 0:10:44OK.
0:10:46 > 0:10:48Whoa! It's holding them up.
0:10:48 > 0:10:50It's like magic.
0:10:50 > 0:10:54It seems like magic, Bud, but it isn't.
0:10:54 > 0:10:56It's clever building.
0:10:56 > 0:10:58So what do you feel in your arms?
0:10:58 > 0:11:00They're being pulled.
0:11:00 > 0:11:03Just like the beams on top of the bridge.
0:11:03 > 0:11:06And what does it feel like the poles underneath are doing?
0:11:06 > 0:11:09- Pushing my arms up.- Exactly.
0:11:09 > 0:11:13So your arms on top are pulling and the poles underneath are pushing.
0:11:13 > 0:11:17And that's what's holding up the middle sections of the bridge.
0:11:17 > 0:11:19Well done, experimenters.
0:11:23 > 0:11:26So, your question was, "How does a bridge work?"
0:11:26 > 0:11:28and I think we've answered it.
0:11:28 > 0:11:32We found out that the Forth Bridge is a cantilever bridge.
0:11:32 > 0:11:34Cantilevers are only held up at one end.
0:11:34 > 0:11:37The longer the cantilever gets,
0:11:37 > 0:11:41the more difficult it is for it to hold something up.
0:11:41 > 0:11:44When there's weight on it, the beams on top pull and the beams
0:11:44 > 0:11:50underneath push so the bridge can hold up heavy things like trains.
0:11:50 > 0:11:53So, I hope that's answered your question.
0:11:53 > 0:11:55ALL: Thanks, Nina. Bye.
0:11:55 > 0:11:58You're welcome. Bye.
0:12:01 > 0:12:05If you want to know more about the science that's all around us,
0:12:05 > 0:12:08go to the Nina section on the CBeebies website. Have fun.
0:12:08 > 0:12:15# Superstructures, superstructures Superstructures, superstructures
0:12:15 > 0:12:17# Some of them are tall
0:12:17 > 0:12:19# Some of them are wide
0:12:19 > 0:12:23- # They're bumpy, lumpy, wiggly too - Wiggly too
0:12:23 > 0:12:25# Some of them are strong
0:12:25 > 0:12:27- # Some of them are small - Like me
0:12:27 > 0:12:30# They're windy, whirly, whooshy too
0:12:30 > 0:12:32# All around
0:12:32 > 0:12:33# Look over here
0:12:33 > 0:12:37# Build it, stack it, pile it up
0:12:37 > 0:12:41# Come on, let's get building
0:12:41 > 0:12:45# Race it, hold it, make it stick
0:12:45 > 0:12:48# Come on, let's get building
0:12:50 > 0:12:52# Come on, let's get building
0:12:55 > 0:12:57# Some of them are cosy warm
0:12:57 > 0:12:59# Some of them are chilly
0:12:59 > 0:13:03# Keep us safe and hide us too
0:13:03 > 0:13:07# Some of them are just for fun or help us to stay dry
0:13:07 > 0:13:10# They're underground and high up too
0:13:10 > 0:13:12# Look around
0:13:12 > 0:13:14# Over here
0:13:14 > 0:13:17# Build it, stack it, pile it up
0:13:17 > 0:13:21# Come on, let's get building
0:13:21 > 0:13:25# Race it, hold it, make it stick
0:13:25 > 0:13:28# Come on, let's get building
0:13:30 > 0:13:34# Come on, let's get building! #
0:13:34 > 0:13:37And remember there are superstructures everywhere,
0:13:37 > 0:13:40whether they're big or small, wide or tall,
0:13:40 > 0:13:42we can all get building.
0:13:42 > 0:13:44See again soon. Bye.
0:13:44 > 0:13:47Bye. Get building!