OK.
You're sitting in a soft comfy chair, reading a book in your lap.
The book stays put, and you eventually start to get sleepy, because
there's almost no acceleration happening.
The chair you're sitting in is seat #27B in a huge jet taking you to visit
your grandparents who live a thousand miles away.
The airplane is maybe 7 miles up, passing over the ground at nearly
500 miles per hour, flying straight, level, and fast !