ELI5, why if you jump inside a moving train you will land on the same spot, but if you jump on the roof of a moving train, you land on a different spot?

Question

seen it on twitter and I can’t get my head around it
EDIT: thanks guys I get it now 😅

In: Physics

Answer 1

In most cases you’ll see in high school physics, both should give the same result. But there is a big factor that high school physics (and depending on your field, uni physics) igbores: air. When you jump inside a train, the air inside it is moving along with the train as well. But the air outside of the train is still with respect to the ground, or moving with the speed of the train, in the opposite direction, with respsect to the train. The air then pushes against you, and when you jump, it blows you back. Of course this depends on how fast the train is going, and how strong the wind blows (and in what direction), but in general, that’s what happens.