Quote (card_sultan @ Oct 26 2016 01:58pm)
So if you fly a in a hot air balloon for a 4 hours and the earth is really spinning at 1000mph - why dont you travel 4000miles?
Because the hot air balloon is also spinning at 1000 mph. And everything around it (including the air) is spinning at 1000 mph. But because everything is spinning at the same speed, everything ends up moving together and not hitting each other.
Pretend that the Earth's surface and the atmosphere are like two trains that are running side by side, at exactly the same speed. Even though both are moving very very fast, when you sit on either of the trains and look at the other it will appear to not be moving at all.
An airplane is like a person who's sitting on one train initially (the ground) and then takes off by jumping to the other train. Because the trains are moving at the same speed, he can easily make the jump, it will be like jumping from one stationary object to another. Relative to each other, the trains ARE stationary.
Now he starts running through the train at 10 mph. This is like an airplane running through the air. Amazingly, the person doesn't suddenly get smacked by the train he jumped on to. He's still perfectly OK, and relative to the first train he's moving at 10 mph. But relative to something that's NOT on the trains, he's moving very very quickly because the train he's on is moving very very quickly. So even though our train is flying through space at 50,000 mph, we can still move back and forth at much slower speeds and everything's OK.