Radius means, from the center of the Earth, a circle, you want me doing these Chop stick plastic wraps, drawing you a circle, on Earth Crust, one pavement road, one from your Eyes, your entire body are straight down to different angle of that Earth middle core.

Its curve. But it will be forever straight to you, in the reality, because your eyes and your body, to your foot, to the concrete roads are glue together.

Never failed.

It is curved.

Its up in the air like the birds.

You didn't jump on the same step where you going forward, you are spinning in the air, to land at? Never a straight line like the pavement road, you saying the Olympia those ball human or on the 單槓

 

This is nothing to do with you imagine how to invention on the Physics Periodic table? I told you they use the same periodic table already. 

Your 1920 science? Those you use math and equation to ....theoretical those property and you go to Equator, ....like I always say, how the Earth rotate, that will be your speed, Per Day Time.