Dave - I've been on flights where the ground speed varied from 450 to 650 knots. There was no feeling of acceleration on any of those flights other than take off, ascent, descent and landing. I suspect you have your physics wrong if you think anyone on an aircraft will feel a change in velocity because it changed wrt to the ground during the cruise. The frame of reference is the aircraft, not some point on the ground.
I do have a little bit of background in physics if you had taken the time to do a little research. It's a shame; I've asked for help on this site and also offered my advice on this site, but to come across someone who 1) didn't read my posts carefully and 2) doesn't understand Newtonion physics but insults me anyway, well, that's your choice.
For your info, I have used Newton's laws to find, track and take spectrosopic data of space debris among other things. I think you should sit back and reconsider your posts.