Rainbow Dragon Newtons Cradle

I've always been fascinated with the Newtons Cradle, one of the most mesmerizing inventions ever made. In fact, it reigns supreme as the world's most mesmerizing desktop toy. However, it isn't the most aesthetically pleasing. Of all of the Newtons cradles I've seen none of them ever stepped out of the textbook design and in today's society this surprised me. When brainstorming my project, I decided to change this. I, Anaia Wallace am proud to present my dragon-themed Newtons Cradle. 

For this project you will need:

Two 9 inch by 3/4 inch wooden dowels

Four 6 1/2 by 3/4 inch wooden dowels

A 10 by 3.5 by 3/4 inch wooden base

Nail gun

drill

3/4 inch drill bit

1 inch metal balls

paint

paintbrush

colored yarn

modpodge

level

ruler

sissors

hot glue

soldering iron

solder

fishing line

TinkerCad

A 3D printer

The first thing that you should do is sketch and research your idea. I usually draw two sketches: one before and one after researching my project. The first sketch is my original idea on paper without acknowledging the boundaries of science. My original plan is to use 3D-printed hollow balls suspended with yarn from a popsicle stick frame. I will 3D print the dragon's limbs. Next, I will research the physics aspect of this project.

Newton's cradle works through the conservation of momentum. So, when you lift up one ball and let it go the momentum is conserved and transferred to an outgoing ball in order to conserve momentum. But if that's true then why when one ball is released two or three don't fly off the end? The simplest way to explain this is to think of it as masses that are connected through tiny springs. When you release two balls and they collide, a shock wave is sent in both directions that propagates the length of the system. The wave goes through the balls and when it hits the end it reflects until it's gone through the number of balls in the system. This is why when you release one (1) ball only one (1) flies off the end or when you release two (2) balls only two (2) fly off the end.

Mass also might affect the cradle. One of my biggest problems was the extra weight of the dragon wings head, feet, and tail. Each ball must have enough weight to move the other balls. Because the 3D-printed parts were very light, this didn't cause much of a problem.

As the balls swing, they lose energy and eventually come to an end. In my prototype, I compared using yarn and a fishing line to hang the balls. The fishing line yielded the best results because it didn't have as much friction as the yarn.

After this, I sketched a modified version of the pendulum this time taking into account my research. The plan for this build is to hang 1-inch metal balls with fishing lines from a wooden dowel structure.

Next, you should build the structure. I used four (4) 6 1/2 by 3/4 inch wooden dowels, two (2) 9-inch by 3/4 inch wooden dowels, and one (1) 10 by 3.5 by 3/4 inch wooden base. The materials that you use for the structure depend on the materials you use for your balls. For example, my prototype popsicle structure crumbled with the weight of the one-inch metal balls that I choose. I used a nail gun to attach two of the shorter dowels to the ends of each of the larger ones. It should look like a rectangle without the bottom. Make two of these, (pic 1). Next, draw a horizontal line 1/2 an inch away from the edge of the width of the base. Next, I marked a vertical line 3/4 inches from the long side of the base on each side. There should be two sides of a square, (pic 3). In the middle of this drill a 3/4 inch hole. Repeat this on the other side. I have provided a picture above for reference. The four holes are where you will insert the dowel structure that you previously made.

This step took me a while since I'm not very skilled with Tinker Cad however because I can draw, I used a convertor to import my 2D drawings into Tinker Cad. I then created several 1-inch hole ball in Tinker Cad, positioned each dragon part on it as I would do with the physical metal balls and joined them. If you aren't familiar with the group feature on Tinker Cad when you group a hole object with a solid object, there is a hole in the solid object. This way, when I printed it, there was a curve so that it would snugly fit onto the balls. Picture 5 was a failed attempt at the dragon head but unfortunately it was too big and stopped the ball from swinging.

Next, I themed each ball and its corresponding dragon part a color of the rainbow as seen in the chart below. To paint them, I used acrylic paint and mod podge. I attached the parts to the balls with hot glue, but I had to sand the balls because they were too smooth and shiny. I also painted the base of the structure like the sky with white clouds and coated the paint with mod podge so that it wouldn't scratch.

I soldered the string to the middle of the balls leaving enough space on each side to attach it to the structure.

I wrapped each color of yarn around the structure. Before doing this mark every one inch on the top dowel. When you wrap the yarn leave a space at every mark this is where you will tie the string. You can get colored yarn, but I chose to dye white yarn myself. How you decorate your Cradle is optional so you can skip this step.

Tie each side of the string to the one-inch marks that you made previously. The balls must hang evenly so take your time on this step.

Start by pulling back one ball. The further you pull back the ball, the more potential energy you will give it.

Release the ball.

Watch as the energy and momentum transfer from the first ball to the last ball in my short video here.