🏎️ Simple Motor Car
Build a cardboard car that zooms using a little DC motor and a propeller.
🧰 What you need
- 1 small hobby DC motor (1.5–6 V)
- 1 small plastic propeller that fits the motor shaft
- 2 AA batteries in a holder with a switch
- A piece of stiff cardboard about 20 × 8 cm
- 4 bottle caps for wheels
- 2 drinking straws and 2 wooden skewers (axles)
- Tape, hot glue (adult only) or strong double-sided tape
🔧 Let's build it!
- Tape two straws across the bottom of the cardboard, one near the front and one near the back.
- Slide a skewer through each straw. These are your axles.
- With an adult's help, poke a small hole in the middle of each bottle cap and push them onto the ends of the skewers. Spin them: they should turn freely.
- Tape the battery holder on top of the car, in the middle.
- Attach the motor at the back end so the shaft points backwards, past the edge of the car. Push the propeller onto the shaft.
- Connect the motor's two wires to the battery holder's wires.
- Put it on a smooth floor, switch on, and watch it zoom! If it goes backwards, swap the two motor wires.
🔬 What's happening?
A motor turns electricity into motion. Inside are magnets and coils of wire. When current flows through the coil, the coil becomes a magnet too, and it's pushed and pulled by the other magnets so it spins. The propeller pushes air backwards, and the air pushes the car forwards (that's Newton's third law!). Swapping the wires reverses the current, so the motor spins the other way.