Did you know that when paper is placed to stand up, even a single sheet of paper can hold the weight of a few books? In this experiment, we will test how many books one sheet of paper can hold and explore why and how paper of the same size and thickness can hold different weights just by being folded into different shapes!
Materials:
Books, three sheets of paper of normal thickness, sellotape or masking tape, scissors
Time Estimated:
10 minutes
Directions:
Fold one sheet of paper into a square column with four even segments on the sides. Tape the edges together from top to bottom.
Repeat the process to make triangular and circular columns, each using only one sheet of paper as well. When making all the columns, try to keep the overlap of edges to be the same.
Now it’s time to test the strength of each shape! Start with your skinniest book, and carefully place it on top of the column, so the book is in the middle of the pillar.
Gently add more books until the column collapses.
Repeat the exact same process on the next column, placing the books down in the same order. See which column lasts the longest and can hold the most books!
Think Like A Scientist!
Did you observe that the circular column was the strongest? Why could paper of the same size hold more weight by changing its shape into a circle?
Would a circle still be the strongest shape if it was tested with other shapes, like a pentagon for example?
How Does It Work?
From the fact that the pillars we made are hollow in the middle, we can tell that the flat sides of the pillar do not hold the weight of the books placed on top, but rather the edges where the books actually touched and sat on give the columns strength. While a triangle only has three edges to split the weight, and a square only has four corners, the round shape of a circle does not have any corners, so in a way it can be viewed as having an infinite number of “edges” that help to distribute the weight. When the book is placed in the middle of the pillar, the center of its gravitational force is also placed in the center of the circle. Since the edges of the circle are all equally far away from the center, the force of gravity will be distributed evenly. As a result, each tiny segment of the “infinite” number of edges on the circle carries much less pressure, and therefore the circle can hold more weight than the other shapes.
Further Exploration:
Often, the pillars we see in everyday life are cylindrical. This is because circles have the most strength to support the weight of the pillar. Since a pillar’s purpose is to hold weight in order to create an open space below, engineers would more likely choose a cylindrical pillar than a square one, for example. Some parts in a square would be farther from the center and have a less equal distribution of the force than other parts, making it a less efficient design. Most pillars are also constructed with large thickness for a similar reason —the thickness provides strength by spreading the weight over a wider area, further distributing the total force and increasing stability!
Looking for more fun at-home STEM activities for your young scientist? Check out our workbook full of exciting science experiments and empowering activities!
