 Hi, welcome to The Mix, the teen center at the San Francisco Public Library. My name is Illiana and I'm your host for our latest challenge series, STEM Challenge Yourself. Our amazing librarians have some fun and creative projects for you to try at home. Today's project is going to be colorful, interactive, and using some of those household items. I think you're ready. Hi, thank you, Illiana. My name is Megan and I am a children's librarian here at the San Francisco Public Library. Today we're going to talk about inertia and force. Inertia and force, what is that? Those are some big words. So we're going to go over here and look at the definition. We have inertia, which is the resistance of any physical object to any change in its speed. And we have force, which is an influence tending to change the motion of a body. Inertia and force were observations explained by a 17th century scientist named Sir Isaac Newton. He called them the law of inertia and we have Illiana over here who has a sign for me. I'll read it for you. The law of inertia is a body at rest tends to remain at rest and a body in motion tends to keep on moving at the same speed. So that's a lot of big words. What on earth does it all mean? Let's see if I can show you an example. Check out this pom-pom. The pom-pom is just sitting there. It is not moving. It is at rest. And to quote Sir Isaac Newton, we can say, a pom-pom at rest, days at rest. Now we're going to drop the pom-pom. Oh, look, it hit the table. Did you guys think it would keep going straight if the table wasn't here and continue even further if the floor wasn't here? If you said yes, you are correct. An object in motion tends to stay in motion. Or in this case, a pom-pom in motion tends to stay in motion. Is there a more interesting way that we can describe this phenomena? Yes. Let's pretend that this pom-pom is a rocket and we need to launch it into space. How will we get it up there? Well, in this case, we could try to push it or we could try to throw it, which are okay, but don't you think it'd be more fun to make a launcher? Yeah, let's make a launcher. So I have some tubes right here, some cardboard tubes. And we're also going to need some balloons, and then we need our pom-poms here. And how we're going to make this launcher is we're going to first tie a knot and the skinny end of the balloon. And if this is too hard for you to do, I'm sure you can find an adult to help you. Then we need to cut off the tip of the balloon. So we do that with some scissors. Same thing, you can find an adult to help you if you need it. Then you take the balloon and you stretch it over the cardboard tube. And then you put a pom-pom inside. Then you pull it back and you let it go. We have our pom-pom launcher or a rocket launcher. So do you want to launch them back at me, Eliana? I would love to. OK, it's so much fun. OK, ready? Three, two, one. Hey. So how did we make the rocket or the pom-pom move? We applied some force to it. Let's do that one more time. There we go. So everybody, that is force and inertia. Thank you for coming and listening today. If you have any other questions about force, inertia, the law of inertia or any of Newton's other laws, because we had a couple others, please look at the information below. Eliana? Thanks, Megan. That was great. That was a lot of information, but you can go to ffpl.org for more tips and tricks on how to stay STEM tested. Thanks for tuning in. See you next time.