So I was taking the bus the other day and i started thinking about this. If you're standing in a bus, and the bus starts to move, you'll stumble forward if you're not creating enough force opposite the direction of the bus' movement. So why does this happen? This is my theory: The static friction from the floor of the bus causes you to move forward along with the bus. But there's also the force from the air behind you, that is caused by the back of the bus pushing the air inside the bus forward. So the air inside the bus, being pushed by the back of the bus, pushes on you. So there are two forces acting on the passenger, the static friction from the floor of the bus, and the force from the air behind the passenger, whereas on the bus itself, there's only one force acting on it in the beginning, which is the static friction from the road. So since in the beginning, there are two forces acting on the passenger and one force acting on the bus, you accelerate at a higher rate than the bus, causing you to stumble forward. Am i completely wrong about this?