It’s the last one flight of the day and the plane is pretty empty. So you’re thinking, maybe just move up a few rows where there’s a nice window seat with a view unobstructed by the sash.
Not so fast, motherfucker. The flight attendant says it’s not possible. You must stay in your assigned seat or you will mess up the weight distribution of the plane. Really? Would moving one person change normal size? Yes, you know where this is going: The answer to this question requires a lot of amazing physics. So let’s go!
MassEdit Center
People often say that the center of gravity of an object is where all the gravitational force is. That’s a fair working definition, and you can use it to solve many physics problems, but it’s not entirely true. In fact, the force of gravity pulls further all parts of an object, not just one point.
(Quick side note: We actually look at center of gravitynot the center of gravity, but in a constant gravitational field like here on Earth, they are the same.)
If you really want to understand the center of gravity, you have to think about it torque. Looking back at Newton’s second law, it says that a net force changes the motion of an object (Fnetwork = mass × acceleration). So if the net force is zero, the motion of the object will not change. If it is moving at a certain speed, it will continue to do so. If it is at rest, it will continue to rest.
Here’s a little experiment: Place the pencil on a flat table and then, taking two index fingers, push from opposite sides, right into the center. It just stays there, doesn’t it? Since you are applying equal and opposite forces, the net force is zero. But what if you push it like this:
Pencil pusherGraphics: Rhett Allain