Length of Project:
Project theme:
Suitable for grades:
Tools & Materials
Material List
  • Toy car (1 or more)
  • Plastic pop bottle cap, or similar
  • A small strip of thick fabric felt, or similar
  • Hobby motor (6~V) with lead wires (and alligator clips)
  • 4xAA battery holder
  • 4 AA batteries
  • Found materials to make a base for hobby motor (i.e., snap blocks, cardboard, etc.)
  • Optional:

  • Switch
Tool list
  • Small nail or awl
  • Hot glue gun and glue sticks
  • 2 x meter sticks (or one-meter stick and one straight edge of similar length)
  • Electrical tape
  • Optional:

  • Variable DC power supply
  • Wood working tools to make a base, i.e., saw, drill, hammer, etc.
  1. Make a tiny hole in the center of the pop bottle lid with a nail or awl.
  2. Drop a bead of hot glue on the tip of the hobby motor axle, then push the pop bottle cap over it so that the open part of the cap is facing AWAY from the motor case. Make sure not to glue the axle to the motor case. Apply more glue inside the cap to secure it to the axle.
  3. Hot glue a strip of felt around the perimeter of the cap, then cover it with a few layers of electrical tape.
  4. Hot glue your motor onto a solid block or base, ensuring that the pop bottle cap sticks out and can spin freely.
  5. Build up the base for your hobby motor, testing the height of it with your toy car. You want the pop bottle lid edge to spin about 1mm lower than the height of your toy car, so you can squeeze the car underneath to be accelerated.
  6. Place your meter sticks side by side along a smooth surface, making sure there is enough space between them for your toy car to freewheel.
  7. Insert the batteries into the battery holder. If your motor leads have alligator clips attached, clip the red wire to the red wire and black to black. If you are using a switch, wire this in between one of the battery holders’ wires and the hobby motor wire.
  8. Turn the motor off and position it at “0 cm” on the meter stick. Turn your motor on and play with pushing your car under the cap to send it racing along the meter stick track. If necessary, you can reverse the motor leads to make your motor turn spin in the opposite direction.
Extension Challenges
  1. Write a paragraph or make a poster outlining a real-life application of this type of propulsion system in their community (i.e., in place of the T-bar at the local ski hill). Next, address three safety concerns that would need to be considered in the design of this machine. Finally, students predict and address potential community concerns over whether their invention is environmentally “friendly”, sustainable or not.
  2. Redesign the accelerator to incorporate two hobby motors to increase the acceleration on the toy cars.
  3. Design and build an automatic launching device that pushes the car through the accelerator.
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