Raikia

Transcription

Let's see... my son bought this toy from the pound shop a few days ago, and he's had some fun throwing it around. The thing is, it's quite simple toy and it's one you can make yourself at home. You can make it using things you probably have anyway like yoghurt pots, plastic bags, wool or string. The great thing about making your own is that you can experiment with the design to see what makes the best kind of parachute. What does the parachute do? When it opens up it makes a sort of ginormous circle. It goes 'swoop swoop swoop' and flop! So what do you think would make this a better parachute than it is? Some time of thick - but not too thick - cloth, so the wind gets caught in it but it still falls down. So you want it to be kind of light, but kind of thick at the same time? Do you want to try and make a thick parachute? Yes! What we're going to do, so we can see which one is better, is make two the same size. You're going to make this one, I'm going to make this one, and we'll be sure it's not just the size that makes the difference. Shall we see if these are the same? Let's put one on top of the other. You can look at the size, the material you're using, the length of the strings... You can change the passenger! If you want make it a bit more interesting and add some danger you can always make the passenger an uncooked egg and see if your design is good enough to get the egg safely to the ground. You can choose the design, but I'm going to show you a really simple one. because I want it to be round, I'm going to cut the seam off the bottom of this bag. I don't want it to be too big this time, so I'm just going to cut a square. I quite like the idea of it being round so I'm going to fold it in half. It's really hard to cut a circle freehand, so round off the edges You can see it's kind of circular. Now I'm going to cut the strings. I find the easiest way to make sure they're all the same length is to keep matching them to each other, like this. I'm using four because it's quick, you can use more if you think that would work better. So now I've got my strings, I'm going to attach them to the basket, in this case a yoghurt pot but basically any small container. Sellotape them to the corners. Once you've done that, the easiest way to center it so your strings are evenly spread, is to put the pot upside down in the centre, and then attach the strings evenly around the parachute. And that's your basic parachute! Let's go test these! Right then! If we're going to test which one is better, we need to drop them from the same height at the same time. Okay. The job of a parachute is to make things move more slowly through the air. We don't normally notice the effect of the air when we're just walking around, but on a windy day, or if you stick your hand out of a car window, you can feel the air pushing against you in the opposite direction. This is called air resistance. Three, two one! And yours has splattered! If I drop this scrumpled ball of paper, it falls quite quickly, but if I drop a flat sheet, it drops quite slowly. That's because it's got a larger surface area and it has to push more air out of the way. Parachutes make use of this effect and generally the larger the surface area the slower it will fall. I'm not sure how precise our experiment was earlier, but it certainly entertained the neighbors. It was a really good way of getting Alex thinking scientifically, especially about things like fair testing. And it was really enjoyable way of spending time with him in the summer holidays.