Imagine you and your furry friends are playing fetch inside a huge, enclosed dog park that can move, like a giant, mobile playpen. While you're playing, the dog park starts to turn.

When you throw the ball in midair, and the dog park turns, the ball appears to move along with the dog park. This is because the ball, you, your furry friends, and the dog park are all part of the same moving system. It's like when you're running with a toy in your mouth – the toy moves with you because it's part of your system.

In the case of the airplane, the same thing happens. When the airplane turns, the air inside moves along with the airplane. Since the ball is surrounded by the moving air, it also moves along with the airplane. To you and your friends inside, it seems like the ball is following a straight path, even though the airplane is turning.

So, if you were inside a big enough airplane and threw a ball while the airplane turned, the ball would appear to continue moving in a straight line, just like it would in a stationary dog park.