Halloween Rock Painting for Kids using Physics and Forces!

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A few months ago, my son’s monthly Tinker Crate project was building a spin art machine! Do you remember those from when you were a child? I do! I loved watching all the patterns and shapes just a drop of paint could make when it moved in a circle. The Tinker Crate project taught my son how to build a battery powered circuit that spun a motor. He learned about resistors and their affect on how fast the spin art spun. He first started by adding one resistor in the circuit, and then saw the wheel of the spin art machine spin a little slower. He then added two, and then three resistors to the circuit, and watched as the wheel spun slower and slower. He learned resistors do exactly what their name says. They resist the flow of current. In other words, they slow down the current flowing to the motor, making the wheel spin slower.

While I watched my son play with his creation, I noticed the patterns at the slower speeds looked a lot like a spider. Then I wondered if we could use a spin art machine as rock painting for kids. More specifically to paint a spider on a rock.

Halloween Rock Painting for Kids using Physics!

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It took a few months for us to finally test out my idea, and by then I had lost our hand made spin art machine. So I did a quick amazon search, and found this simple spin art machine. It took a little trial and error, but we were able to find a way to paint the rocks just in time for Halloween!

Step 1: Select 6 to8 the rocks to paint. Wash and towel dry each stone. We used these small white pebbles.

Step 2: Using a hot glue gun, place a small dot of hot glue in the center on one side of a rock. Glue the rock to the center of the spin art machine, and let dry.

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Step 3: Draw a circle with the paint provided in the spin art kit, and color it in with the paint.

Step 4: Turn on the spin art machine, and watch as the paint slowly moves out away from the center.

You can add more colors to a rock, or use just one color.

Step 5: Turn off the spin art machine, and wait for it to come to a complete stop. Carefully remove the painted rock from the spin art machine. We used a butter knife to slowly peal the rock off. Remember to also take off the dot of hot glue on the spin art machine. Set the rock off to the side to dry. We had a lot of fun painting our rocks! My two oldest sons took turns trying different colors and designs, and this is how all the rocks turned out!

Step 6: Once the rock is completely dry, glue 8 googly eyes to the middle of the spider.

Step 7: Repeat steps 2 through 6 to the remaining rocks.

My boys loved making their spiders, especially trying different colors and designs!

How is the spider made?

When the paint is spinning, it has the same circular velocity (or speed) as the spin art machine. But when the motor slows down, the paint on the rock continues to move at the same speed. So the paint leaves the rock behind, and keeps moving at the faster speed. When you watch the video, you’ll notice that the paint does not start “dripping” from the paint circle until the spin art machine starts slowing down. At this time, the paint continues to move at the speed the rock had been moving, while the rock slows down. Its the same idea as when you moving in your car, and it suddenly stops. You continue to move forward at the car’s speed before it stopped, but the car immediately stops. If you didn’t have seat belts, then you would continue to move forward, even though the car is not longer moving forward. Good thing we have seat belts!

Let me know how your spiders turn out! I would love to see your ideas on how to make even creepier spider rock paintings for kids!