Rubber Band-Powered Car

SUBMITTED BY: Drayton Valley Public Library

PROGRAM DELIVERY: Directions should be recorded and posted (website, social media, YouTube – whatever your patrons are accessing) so that they can be accessed / replayed as needed. Could be livestreamed or in a video chat in addition for a more interactive experience. Comments while livestreaming or video chat allow for brainstorming & problem solving with the patrons.

STAFF INSTRUCTIONS/TIPS: Practice first! Make your own car so that you can experience the process and see what types of problems could occur – if you are doing an interactive program (livestreamed or video chat), this will help you better brainstorm & problem solve with patrons. Learn a little about the science behind how the car works (potential energy / elastic potential energy, kinetic energy, friction) – be sure to explain the scientific concepts behind what you are doing! If you are preparing materials (craft kits, etc.) for the patrons, you may want to precut the hole in the bottom of the box and punch the holes in the side of the box. Do not flatten the boxes as this decreases the strength of the box – jello or macaroni & cheese boxes work best. Try to do the least damage to these boxes when opening them. The end that was opened will need to be taped shut again.

AGE GROUP: age 6+ (adult assistance may be needed with cutting & making elastics behave!)

TIME REQUIRED: 30 min (from scratch with decorating) – 10 min (box prepared, minimal décor)

SPACE CONSIDERATIONS: Table required for work/to run program. May wish to move to the floor to test car.

MATERIALS REQUIRED: Per car:

1 cardboard box (jello or macaroni & cheese or similar best – not flattened)
4 milk jug lids (soft plastic best)
1 popsicle stick (half sized – short – popsicle stick best)
2 bamboo skewers
5 elastics (regular type – can include extra elastics in case of snapping)
Paint or any type of decorations desired

INSTRUCTIONS (FOR PATRONS):

(You do not need to turn the box inside out as in the picture – that’s just something I tried. Also, I took apart my already constructed car which is why you see decorations, etc in the photos.)

Create an opening: Cut a rectangle out of the bottom of the box – leaving about one inch of the bottom of the box intact at each end. (This allows for more stability of the body of the car.)
Punch axle holes: Using a single hole punch, create the four holes for the two axles to go through on the sides of the box. Make sure the two holes for each axle line up with each other. The holes should line up to about the middle of the one inch section we left intact at each end of the box.
Prepare the anchor: Create a slit for the popsicle stick in both the top & bottom of the box (car body). This slit should be between the end of the box and the placement of the axle (you may want to put an axle in the holes just to make sure of your slit placement). Insert the popsicle stick to make sure the holes work. Remove the popsicle stick (and axle).
Decorate the body of the car if desired – this is a good point at which to paint. The car can always be decorated later, but it may be easier to do this without the axles or tires attached.
Prepare the tires: Using something pointy (ex. end of bamboo skewer, or thin screwdriver, or pen) poke a small hole in the middle of each of the milk jug lids. Do not make the holes very large – they will need to fit snuggly against the axles.
Prepare the axles: You will probably need to shorten the axles. They should extend about an inch past the box on each side when inserted into the axle holes.
Anchor the elastic: Cut one elastic so that it is a straight line. Tie one end of the elastic to the popsicle stick. Insert the popsicle stick into the slits so that the elastic is inside the box. (Put one end of the stick into one slit from the inside of the box, slide the popsicle stick down until you can insert the other end of the popsicle stick from inside the box. You may have to roll the elastic up and down the popsicle stick to facilitate this process.)
Tie the elastic to the axle: Tie the loose end of the elastic to one of the axles (the axle does not need to be inserted into the axle holes for this). You want to tie it so that the elastic has no slack, but in fact is a bit taut when the axle is inserted into the axle holes that are farthest from the popsicle stick anchor. The knot must also be very tight against the axle – if it is not, you will not be able to generate any power with the elastic. Insert the axle into the axle holes.
Attach the tires: Insert the other axle into the axle holes. Attach the “tires” (milk jug lids) to the axles. The tires should not be right against the body of the car.
Finish the tires: Wrap a rubber band around each tire. This gives the car traction when it tries to move across the surface.
Test your car: Push down gently on the car and pull the car back along the ground. Release! The car should travel forward. If this is not working, turn the car around and try the same thing again. If this is still not working, check that the elastic is tied tightly against the axle. The elastic may need to be tightened from time to time with excessive play.

BOOK/MEDIA TIE-IN (OPTIONAL): Any non-fiction books about cars! Any books about cars from the movie “Cars” – or the “Cars” movie itself. Any stories with cars in them!

Non-fiction (on Hoopla) – Amazing Rubber Band Cars (by Mike Rigsby)

Non-fiction (on Hoopla) – The Inventor’s Secret: What Thomas Edison Told Henry Ford (by Suzanne Slade)