Balancing Nails | Balancing Nail Puzzle Experiment

Balancing Nails: A Balancing Nail Puzzle Science Experiment

Can a simple trick with nails teach you an important scientific lesson? Discover how the precarious center of gravity that’s provided by the stability of just one, single nail head can provide a mind-bending gravity lesson.
The object of this balancing nail puzzle is to balance a dozen nails on the head of a single nail. All of the nails have to be balanced at the same time and they cannot touch anything but the top of the nail that is stuck in the base. Are you up for the balancing nails challenge? Let’s go!

Experiment Materials

Experiment Videos

Experiment

1

Hammer one of the nails into the center of the block of wood. It’s a good idea to measure and predrill the hole to avoid splitting the wooden block. It’s important that this nail be standing as straight as possible.

2

Place the wood block flat on a desk or table. The challenge is to balance all of the nails on the standing nail in the wooden block. To win the challenge, none of the 11 nails may touch the wood block, the desk or table, or anything else that might help hold them up. No additional equipment other than the wood block and the nails may be used.

3

Need help? The trick to balancing the nails has to do with their center of gravity or balancing point. Lay one nail on a flat surface and place the other nails across this nail, head to head as shown in the photograph on the following page. Finally, place another nail on top of this assembly, head to tail with the second nail.

4

Carefully pick up the assembly and balance it on the upright nail. Voilà!

How Does It Work

On Earth, there’s no escaping the laws of gravity. And thank goodness, too — without gravity, we would all float up, up, up — out into space. Gravity is what makes us “stick” to the earth. Sir Isaac Newton was the first to describe gravity in a mathematical equation. This was Newton’s theory called “the law of universal gravitation.” Gravity pulls every object toward the center of the Earth — as if all of its weight was concentrated at one point. That point is called the “center of gravity.” Objects fall over when their center of gravity is not supported. For symmetrical objects like a ball or a meter stick, the center of gravity is exactly in the middle of the object. For objects that are not symmetrical, like a baseball bat, the center of gravity is closer to their heavier ends.
In our balancing nails puzzle, the stability of the nails depended on their center of gravity being right at, or directly below, the point where they rested on that bottom nail. Add too many nails to the left or to the right and they would become unstable and fall off.

This “scientific” balancing nail puzzle is trickier than it looks. The best way to solve it is to think of an idea and then try it out. Even if it doesn’t work, you might think of another idea at the same time. The key is to not get too frustrated and give up. Keep trying. You might even have to sleep on an idea and come back to it the next day. You may want to share your ideas with others to see if they have a different approach to solving the same problem. This problem-solving process is exactly like the scientific method: ask a question, run some tests, ask another question, run some more tests and eventually come to a conclusion. If your experiment or “solution” doesn’t work, that’s OK. Some of the greatest scientific discoveries have been made by mistake!

Take It Further

Slowly remove one nail at a time. How many nails can you remove before the system collapses? Which nails are necessary for this system to remain in balance? If you’re really ambitious, you can try your luck at our large-scale version using landscape nails (often called “spikes”) and a friend as the base. Have a friend hold one of the large nails while you attempt to balance the other 11 nails on the head of the single nail. (Here’s a bit of advice: start with the small-scale version of this balancing nails puzzle, then work your way up.)

Steve Spangler Science and the Balancing Nails Science Experiment

Learning about gravity, force and motion and the laws of physics can be fun, as you experienced in this trick with nails. This is just one of our many science experiments for kids that will give them a hands-on experience with scientific principles that they experience in their everyday lives. Even if you can’t specifically “see” the laws of gravity and physics, you can certainly observe how they’re working around you. Experience these laws first-hand with our online scientific experiment library. Be sure to check out our experiments on forces and motion, energy experiments, all about air and other at-home experiments that will blow you away!

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