Man Overboard
Ryan Yeung
Award: Top 100
School: valhalla high school
Teacher: federico duay
Category: Contrived
Photo #20954
Man Overboard
At first glance, the stack of objects here looks like it should fall instantly. With each object shifted a little farther out than the one below it, it creates a curved overhang that ends with a small model ship. The reason that it stays balanced is due to the center of mass and torque.
For an object to maintain rotational equilibrium, the clockwise and counterclockwise torques must stay balanced. If a book's center is too far beyond the edge of the book that is below it, the gravity produces a large torque on the system, leading it to rotate and fall. However, each book is not balanced by itself. Instead, each lower book supports the combined center of mass of each object above it. Thus, as long as the combined center of mass stays over the contact area between two books, the stack will remain balanced.
The larger, heavier books are near the bottom as they provide a wider base, shifting the total center of mass towards the table. The smaller objects near the top, like the decks of cards, can extend farther from the table as they have less mass, creating less torque. Friction between the books also matters as it prevents the books from sliding before they tip.
This photo perfectly captures the stack at the edge of its stability. It is close enough to looking impossible, but it is still balanced by the physics of torque, gravity, friction, and center of mass.
|
