Welcome to Club SciKidz’ LEGO STEM Challenges!
For the next four days, we’ll be bringing you STEM Challenges that you do by using the LEGOs you have at home. We’ll pose the challenge, give you a little instruction, and then your imagination is the limit! We’d love to see what you come up with, so feel free to post pictures of your creations on our Facebook page!
Challenge #1- Balloon Car
You know what a balloon is, and you know what a car is. But do you know what a balloon car is? It might not be exactly what you think. When it comes to “real cars”, there are a few different for the energy source. The majority of our cars are gas powered. This is non-renewable energy. That simply means that when’s it’s used up, it’s gone. That’s why mom and dad have to go to the gas station to get “new”/more gas when their current tank is empty. The other kind of energy is called renewable energy, and that is energy that does not run out or can be replenished. Some explains are wind powered and solar powered. Electric cars also use renewable energy because although the electricity runs out, it can be replenished by charging it back up.
Now, most LEGO cars you’ve built don’t have an energy source besides you pushing it and it rolling on its wheels (which are simple machines). Today your challenge is to built a LEGO car that can be powered by a balloon– or should we say, powered by the air exiting a balloon. This brings us back to Newton and his Laws of Motion.
Newton’s 3rd Law of Motion
Look at the picture to the right. When the bigger person sits on the end of the seesaw, his weight pushes it down. The reaction is that the tiny critters fly up into the air. For every action there is an equal and opposite reaction. We are going to use this Law of Motion to get your car to move.
Think about a blown up balloon…. When you blow up a balloon and hold it closed. It’s at rest. (This is actual Newton’s 1st Law of Motion). As soon as you let it go, it is no longer at rest (because an outside force acted upon it). But what we want to focus on is where the balloon goes. Think about it for a second. In what direction does a balloon go when you release the air? You’re right, it goes away from you. As the air is being let out of the back side, it’s going to push the balloon forward. The action is the air being let out of the balloon, and the reaction is the balloon moving in the opposite direction. When the balloon is out of air, it stops moving and drops to the floor. The amount of air released is equal to the distance the balloon moves.
Potential and Kinetic Energy…. Both of these types of energy will come into play as you design, build, and test your car. As soon as your LEGO creation has wheels, it has potential energy. That means, it’s not moving yet, but it has the potential to use energy and move. As soon as something happens to get the car rolling, it’s now using kinetic energy, energy that is active. Think back to the blown up balloon. When it’s blown up and you’re holding it, it’s potential energy. As soon as you leave go of it, it’s now kinetic energy because it’s flying around the room. Watch the following video for a refresher and then let’s get started on your challenge!
Your Challenge: Build a Car that Can be Powered by a Balloon
Materials: LEGOs (regular, Duplo, or even generic works; you just need at least two sets of wheels), a balloon