Balancing Nail Puzzle

This is one of my favorite puzzles and it's so simple to build that I decided to share with you all.

If you are a physics teacher you can use this to explain your students how to balance forces.

This is the list of materials that you need to build this puzzle:

• 1 Rasp (you can buy at your local hardware store)
• 1 Glue gun (you can buy at your local hardware store)
• 1 Hammer (you can buy at your local hardware store)
• 1 Rectangular piece of wood (you can buy at your local hardware store)
• 1 Nail 5x125mm (you can buy at your local hardware store)
• 14 Nails 4x90mm (you can buy at your local hardware store)

With the rasp round the corners and remove any wood chips.

Use the 5x125mm nail and hammer it in the center of the wood piece

To insure that the nail stay there glue it to the wood piece using the glue gun.

And now the puzzle is built, time to use your brain!

The object of the challenge is to balance all of the nails on the head of a single nail. All of the nails have to be balanced at the same time and cannot touch anything but the top of the nail that is stuck in the base.

Start to build your structure in a table.

1. Put one nail like in the first picture.
2. Then add nails like in the above pictures.
3. Finally add the last nail in the top of the others
4. Carefully grab this structure and place it on the top of the big nail

Center of gravity: The point were gravity pulls an object down.

Explanation:

For symmetrical objects like a ball, the center of gravity is exactly in the middle of the object. For objects that are not symmetrical, like a nail, the center of gravity is closer to the heavier end.

The stability of the nails depends on their center of gravity being right at or directly below the point where they rest on the bottom nail.