this is the last The day's flight and the plane are pretty empty. So you're thinking, maybe you'll just move up a few rows, where there's a nice window seat whose view isn't obstructed by the wing.
Not so fast, busterThe flight attendant says it is forbidden to do so. You must remain in your assigned seat otherwise you will disrupt the weight distribution of the aircraft. In fact? Would moving a normal sized human make any difference? Yep, you know where this is going: Answering this question requires amazing physics. So let's get to it!
Center of mass
People often say that the center of mass of an object is the place at which the entire gravitational force acts. This is a reasonable working definition, and you can use it to solve many physics problems, but it is not actually true. Actually gravity pulls All Parts of an object, not just a point.
(A quick side note: we're actually going to see this center of gravityNot the center of mass, but in a constant gravitational field like on Earth, they are the same.)
If you want to really understand the center of mass, you need to think about Torque:Looking at Newton's second law, it says that a net force changes the motion of an object (FNet = mass × accelerationSo if the net force is zero, the momentum of an object will not change. If it is moving at a certain velocity, it will continue to do so. If it is in a state of rest, it will continue to rest.
Here's a little experiment: Place a pencil on a flat table and then, taking your two index fingers, press exactly in the center, from opposite sides. It stays there, right? Because you are applying equal and opposite forces, the net force is zero. But what if you apply pressure to it like this:
pencil pusherGraphic: Rat Allen