Although this isn’t chemistry, but rather a little math project, it’s a really cool experiment. Ask someone if they think you can walk through a piece of paper by cutting a hole in it with a scissors. Then show them that you can!
Materials
- 8 ½ × 11-inch paper
- Scissors
Experiment
- Fold the piece of paper so that it is 11 by 4 ¼-inches.
- With scissors, cut where you see the blue lines. The first and last cuts should begin at the folded edge of the paper rather than the open edge.
- Cut along the fold of the paper but do not cut all the way to the end.
- Open up the paper. Can you fit through it?
What’s happening?
When you ask someone if you can walk through an 8½ by 11-inch sheet of paper by cutting a hole in it, they may think that you are going to cut a circle in the middle of the sheet and then try to squeeze yourself into or through the resulting opening. That would be impossible, however! What you need to do is to increase the perimeter of the opening in the paper. The perimeter is the distance that is measured going around the outside of the paper. At best, this would be 8½ + 11 + 8½ + 11 = 39 inches. Your body is bigger than 39 inches around! By cutting the paper as described above, however, you can drastically increase the perimeter, which will allow you to walk through the opening in the paper. The area of the paper (length times the width) remains the same but the perimeter increases.
Extension
What happens if you make fewer cuts along the width of the folded paper, or if you only cut halfway across the paper? Will this activity work if you fold the paper lengthwise so that it is 8 ½ by 5 ½-inches across? How do these changes affect the size of the opening? What happens if you use a smaller piece of paper, such as an index card? Can you fit through an opening in that?
Believe it or not, this activity has applications in physical science and chemistry. When scientists or engineers need to cool something down, they want to expose as much of it to the air as possible. By increasing the perimeter of a sample or container, more of the surface can be exposed to the air over a larger area and it will cool faster. If you have radiator heat in your house you will find the radiator is designed with lots of “fins” that can disperse the heat better. You can see similar fins on the back of a refrigerator to help draw the heat away from the refrigerator and thus cool the inside.
Reference
https://blog.doublehelix.csiro.au/climb-through-a-hole-in-a-sheet-of-paper/
To view past “ChemShorts for Kids” activities, go to:
https://chicagoacs.org/ChemShorts
