 Welcome to Do Try This at Home, brought to you by the Institute of Physics. We're back for a winter special episode as part of our Limit Less campaign with an activity specifically designed to get the whole family together. We are going to be making a snowball slingshot and this activity should be snow trouble at all. You are going to need a bottle, like this one, it needs to get narrower towards the end and have a nice wide lid. A mug or a cup, a marker pen, some sharp-ish scissors, some tape, a balloon. You are also going to need something to launch. I'm going to be using little scrunched up pieces of tin foil and if you want to decorate your launcher I've got some coloured paper here and some colouring pencils to make it super festive. Take your bottle, stick it upside down in your mug, draw around the top. Now use your scissors as a stabbing tool, a grown-up should definitely do this part. And now cut around your drawn line. Check the top of your bottle for jagged edges and cover them with a bit of tape. Now take off your lid, take your balloon and you're aiming to stretch the mouth of the balloon over the mouth of the bottle. This is quite fiddly so you might need to give your young people a bit of a hand with it. This launcher is ready to use but I'm going to decorate mine. When you have a beautifully decorated launcher like mine, take your scrunched up bit of tin foil, drop it inside your launcher, pull the balloon back, release. Maybe challenge your family and friends to a game of snowball slingshot. Don't shoot them at each other. Sam, can I borrow you for a minute? No, thanks. No! My hands are freezing. Can you explain it to your family? Now I won, debatably, because I know the physics behind snowball launching. The first is how the slingshot itself works. When I pull the balloon back, it stretches it out of shape so that when I release, it's into the snowball. It's this flicking force that sends the snowball flying. From the point that the snowball leaves the bottle, the force of gravity controls the path that it takes. If I shoot straight upwards, the snowball starts off quickly but the downward pull of gravity causes it to travel slower and slower until it stops going upwards and starts to fall. The snowball speeds up as it falls back down and lands exactly where it started. But because the snowball doesn't go anywhere, it's not going to win you any points. If I point straight forwards at launch, then we have the opposite problem. Because I'm not firing upwards at all, the snowball starts to fall straight away and so doesn't go very far. If I point diagonally upwards and launch instead, we've got the best of both worlds. The snowball travels up and back down and takes a lovely curved path to the floor. If you want to go the furthest and get the most points, you need to launch at 45 degrees. This is the angle that's in between straight up and straight forwards and this will get your snowball to go the furthest. Now it's totally cool if you don't get the science. As always, have fun together, look it up together, decorate and enjoy the game together as well. If you want to go to our Do Try This at Home website, you'll find the full written up instructions for everything that I've been talking about along with 13 other episodes for you to try out together at home. Thanks very much. Bye-bye.