Slingshot Cars
The slingshot car is an excellent introductory project to illustrate how potential energy is converted into kinetic energy, and the importance of low friction. Just be sure to watch your feet as cars go racing across the floor!
You can find the lesson plan, 1-page project sheet, and more project ideas at STEM-Inventions.com
Project Goal: Students build cars that are rapidly propelled across the floor at least 10 feet.
Design Variables
- Axle width
- Number of wheels
Key Concepts
- Wheel Alignment means all the wheels all point in one direction
- Energy transformation is when one kind of energy turns into a different form
Prep: Bend paperclips into hooks (1 per student)
Safety: Launch cars only horizontally across the floor. Designate a launching area and direction when students begin to test.
Materials
The Engineering Creation Kit has everything you need for this project and many more from STEM Inventions.
Plastic cups (for stackable crash targets)
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The Basic Frame
The frame can be just about any shape and size. I use a rectangular frame for my example because it has about the same proportions as a real car and it's easy to build.
Adding Wheels
Create the wheels by putting a dowel into a straw, then put the plastic wheels onto the ends of the dowel. Wrap a small piece of tape around the ends of the dowel to prevent the wheels from falling off.
Attach the Rubber Band
Use 2-3 layers of masking tape to attach a rubber band onto one end of the frame. This step completes the essential car frame!
Optional: Customize the Car
It's fun to make the car personalized. Use craft cubes and sticks to give it a cool profile.
Set Up the Launcher
Tape a pencil to the floor. Make sure to layer and crosshatch the tape to keep the pencil secure to the floor.
Launching the Cars
- Place the car on a smooth, flat surface with the rubber band pointing in the direction that the car will be traveling.
- Hook the rubber band onto the pencil eraser.
- Pinch the back center of the car frame, pull back, and release!
Safety, Tips and Troubleshooting
- Don't allow your students to fling the cars directly at each other.
- Some students will want to crash their cars into things. Bring plastic cups and stack them into pyramids to make some dramatic and appealing targets.
- If the car is spinning out, make sure the wheels can spin freely, and that the wheels are aligned.