Craft Stick Motorized Car

  Learn about electrical circuits with this simple motorized car.

Materials:

• bottle caps or any other items that can be used as wheels

• straw

• paperclips

• Hobby motor

• 1 AA battery

• Solid core wire (we like telephone wire)

• craft stick

• tape

• a broccoli rubber band, or inner tube cut off
• wooden dowel or bamboo skewer

Tools:

• scissors

• wire strippers

• hammer
• nails

• hot glue gun

Make a hole in bottle cap by hammering a nail through the middle of the cap.  Push the motor’s axle through the hole.  It should be a tight fit.  If it is not a tight fit hot glue the cap in place. We found that a 3D nail makes the perfect size hole for the axle of the motor we use. 

  

Use scissors to enlarge holes for rear wheels if using a dowel. If using bamboo skewers it is not necessary to enlarge the hole. 

Cut dowel to preferred length.  Cut straw an inch smaller than dowel.  Insert dowel into straw and glue rear wheels to dowel. The second photo shows us using corks for wheels and a bamboo skewer for the axle.   Wheel axle should spin freely in straw.

Glue or tape rear wheel assembly to craft stick.

Cut wire into two and strip half an inch of the insulation from both ends of the two wires.  Attach each wire to a paper clip, ensure the ends of the paperclip are pointing towards the wire to prevent scratching the battery. See above photo for correct position.

Pull rubber band lengthwise over the AA battery.

Tape battery to craft stick.

Hot glue motor to end of craft stick and attach wires to motor tabs. Slide one of the paper clipped wires between the rubber band and the positive end of the battery.  Do the same for the second paper clipped wire to the negative side of the battery and watch your car go!

Things to do and notice: 

• Cars might go “backwards” if the polarities (negative and positive) of the battery are attached to the motor in a certain way.  If this is the case switch the wires that are connected to the battery.
• The weight of the battery helps the front wheel gain traction. Using a piece of bicycle inner tube can also help with this.  If the front wheel jumps around too much try adjusting the position of the battery. 

Concepts Involved:

• An electrical circuit is a path for the electrical current to flow. By connecting one wire from the battery to the motor and another from the motor back to the battery you are creating an electrical circuit.
• Conductors and insulators:  Paperclips and copper wire make good conductors; they allow electricity to flow through them with little resistance. The rubber band and the wire plastic insulator resist the flow of electricity as do all materials that are insulators.
• Friction is the force between two objects as they move over one another. 
• Static frictional force is what happens with the wheel attached to the motor and enables the car to move forward (or backward). 
• Kinetic frictional force keeps the object in motion.  The initial force that starts something to move is always greater than the force needed to keep it moving.  The rear wheel assembly has little friction as the axle moves around in the straw.

Focus Questions:

1.      How else can you make the car turn on and off? Try making a switch.

2.      Would the car go faster with a bigger front wheel or bigger rear wheels?

3.      Does it matter if the car goes forward or backwards?  Does the car travel faster one way or another?