Video transcript of Episode 7: Rocket Balloon
On-screen text reads: "Do Try This at Home from the Institute of Physics. Episode 7: Rocket Balloon."
The camera cuts to a close-up shot of Mikey holding a long red balloon. He has blown up the balloon and is holding the neck of it to prevent it deflating. The balloon is also attached to a line of thread above it. We see two bits of drinking straw threaded through the string and the balloon has been taped to the pieces of straw. Some atmospheric music plays.
The camera cuts to a slow-motion image of the balloon flying across the front room. A Lego person is sitting on top of the balloon and looks terrified!
Camera cuts to a medium shot of Mikey who is ready to present the experiment. He is sitting behind a table with a balloon in his hand.
On the table there’s a straw, some scissors, some tape, and a piece of string.
Mikey: "Hello and welcome to Do Try This at Home, brought to you by the Institute of Physics. We’re making these videos because we want to help parents and carers around the UK and Ireland to get their kids excited and curious about the world around them, even when they can’t leave the house.
"My name is Mikey, and I’m still here in my front room. Luckily though I get to make this video for you as it’s about one of my favourite things – space travel! So, get ready to discover the furthest unreachable corners of your front room."
We hear a whooshing noise as the camera zooms in on Mikey.
Mikey: "To make your balloon rocket you’re going to need a balloon. You’re also going to need a length of string, a straw – I’m using a paper straw – some scissors and some tape."
Mikey picks up each item in turn and shows them to the camera. The balloon is deflated at this point, but we can see that it is a long tubular-shaped balloon. He picks up the ball of string.
Mikey: "So before you start, decide how long you want your string to go. It could be all the way across the room, or it could just be a couple of metres."
Mikey unravels some string. He is working out how much string he needs.
Mikey: "So, I’m going to try and see how far I can get a piece of string within my tiny flat. So, once you’ve found your ideal length you need to find two secured points to tie the string to. Bear in mind it wants to be at the right height so the balloon rocket is visible for all your family, and you also need to have enough strength in it so you can have enough tension that it’s in a straight line."
Mikey pulls the string at each end until it forms a straight line.
Mikey: "Once you’ve found your point you can tie one end on. Don’t tie the other end on yet – then you can cut the string."
Camera cuts to show the top of the table.
Mikey: "Next, you’re going to cut the straw into two short lengths. One to about three centimetres/an inch and a half each. Then thread them onto the loose end of the string. Once you have your two pieces of straw threaded onto the string then it’s time to tie it up."
Mikey picks up the scissors and the straw and cuts two short lengths of straw. He sets them aside and places the scissors down. He then picks up the string and threads it through the two pieces of straw. Mikey gets up from behind the table and walks through the open living room door to the hallway. There is a coat hook on the wall, and he ties one end of the string to it.
He then comes back and sits behind the table he was presenting from. We see that the other end of the string has also been tied to a spot beyond the camera.
Mikey: "Next, take two short lengths of tape. Blow up your balloon, holding it shut at one end with your fingers. Now you can actually use a clothes peg, to hold this closed. I don’t actually have one at home at the moment, so I’m just going to pinch it. So, then you’re gonna stick your two pieces of tape in the centre so each of the two short lengths of straw thread upon your string."
Mikey has cut two short lengths of tape which he shows to the camera before sticking them to the edge of the table. He blows up the balloon and holds the neck of it closed.
Mikey: "Now this is a fiddly bit. So, you might want to get someone to help you because what you’re gonna do is just stick the tape onto the balloon like that."
The camera cuts to a close-up shot of the two pieces of straw which are threaded onto the string. There is a gap between the two pieces of straw. Holding the neck of the balloon with one hand, Mikey picks up each piece of tape and sticks it to the centre of each length of straw. He then attaches the top of the balloon to each bit of straw using the tape.
Mikey: "All right now we’re ready to launch."
Atmospheric music plays. Camera shows close-up shot of the balloon attached to the string.
Camera cuts to Mikey pulling the balloon along the string until he gets to his starting point for launch, which is where the coat hook is. Everything is in slow motion. He is still holding the neck of the balloon to stop it deflating.
Camera cuts to earlier slow-motion image of the balloon Lego person sitting on top of the balloon.
Camera cuts to Mikey standing by the coat hook checking the tension on the string.
Camera cuts to a close-up of the terrified looking Lego person sitting on the balloon.
Screen goes blank. We hear a pounding heartbeat.
Camera cuts to a long shot of Mikey getting ready to launch the balloon. He releases the neck of the balloon, and we see the balloon fly along the string towards the camera and beyond. There is a whooshing noise. Then the scene rewinds and we watch the balloon launch again. We see Mikey starting to walk back towards the camera.
Camera cuts to a medium shot of Mikey. He is sitting down in from of the table again.
Mikey: "So, what’s actually going on here and how can you explain it to your family?"
A rocket is a vehicle that carries everything with it that it needs to create a force to push it forwards or in most cases upwards. So, when you’re filling up your rocket balloon, you’re giving it what it needs in order to make itself travel – in this case air.
Mikey is blowing into the balloon to demonstrate his point.
Mikey: "It’s actually quite hard to blow up the balloon because as you’re blowing into it the balloon actually pushes back against you as you blow, and it’s this pushing of the air that makes the balloon move.
Mikey blows into the balloon again. It’s not easy. He pulls a face and says: 'Oh!'"
We hear a whooshing noise. The camera cuts to an image of an inflated balloon. We can see inside the balloon. There are little dots moving around in all directions and bouncing off each other and the walls of the balloon.
Mikey: "Well, that’s because air is made up of particles. There are loads and loads of these particles inside the balloon. They’re whizzing around in every direction creating a force and pushing on whatever they bounce off."
Camera cuts to Mikey who is holding up his own balloon to demonstrate.
Mikey: "They’re hitting each other but they’re also hitting the inside of the balloon. They’re moving left and right and they’re also hitting the top and bottom and these forces cancel each other out and that’s what we call a balanced force and that’s why the balloon doesn’t move."
Camera cuts to the image of the balloon again, the dots are moving around still but this time an arrow appears to the left and right of the balloon, followed by the top and bottom. Each arrow points away from the balloon. The dots disappear and we just see the outside of the inflated balloon.
Camera cuts to Mikey.
Mikey: "So, what happens when we open one end of the balloon? Well, there’s no longer particles pushing against the inside surface of this edge of the balloon because they can escape instead."
Camera shows the image of the balloon again. This time the camera is focused on the neck of the balloon. We can see the dots bouncing around but this time some dots are escaping because the neck of the balloon is open.
But they are still pushing against this side, which means the left-right balanced force is no longer balanced, and it’s this unbalanced force, acting inside the balloon on this edge, which causes it to move along the string.
Camera cuts to Mikey again who points to the rounded end of the balloon that’s opposite to the opening, or the neck of the balloon.
Camera cuts to the balloon. There are arrows pointing from the top and bottom of the balloon as well as the end of the balloon opposite the opening. We hear a whooshing sound. The balloon moves in the opposite direction to the opening and disappears off screen.
Camera cuts back to Mikey.
Mikey: "The same thing happens with real rockets, except it’s fuel, not air, but it’s the same principle. Something can escape one end and therefore creates a force on the other end in the opposite direction and causes it to move."
We hear a whooshing noise. Camera cuts to Mikey again.
Mikey: "Now this is rocket science so if you’re not sure, just have fun with your family test it out together and if you need to look it up just look it up together.
"Thanks for watching this edition of Do Try This at Home and we’ll see you next time!"
Mikey lets go of the balloon in his hand and it deflates. We hear the sound of air being released. The music starts playing and we see Mikey releasing the balloon in slow motion. This time as the balloon deflates, it smacks Mikey in the face. He looks surprised and then crumples up and starts laughing.
The image fades to be replaced by some on-screen text which reads: "Do Try This at Home from the Institute of Physics. For instructions and more Do Try This at Home films visit iop.org/athome. These experiments have not been specifically safety tested for home use, but we believe them to be safe if the instructions are followed. Adult supervision is recommended as appropriate. All experiments are carried out at your own risk."