A point on the earth s equator moves with a speed of 1600 km
By Question:
A point on the earth's equator moves with a speed of $1600$km/h ($450$m/s) due to the earth's rotation about its axis. Thus, all of us are moving very fast. Why we do not feel this motion?
Let us divide ``feeling'' into two parts (i) through outer observation (ii) through physical force/pressure acting on our body.
Firstly, let us understand the outer observation part. When we travel in a moving train, we don't feel/observe its motion until we look outside the window. Looking from the window, we observe moving trees. But our experience tells us that trees cannot move. Thus, we infer from the moving trees that the train is moving in the opposite direction. We observe our motion through trees. The same is true for the earth. We need to look through the window of the sky. We don't find trees but the sun, the moon, and the constellations, all moving. We can infer the earth's motion through these heavenly objects. Next time when you look at the sun, think of the direction of your motion. It is opposite to the direction of motion of the sun.
Secondly, let us understand the physical force/pressure acting on the body. We don't feel the force acting on our body, but we feel the change in the force. The atmosphere is applying huge pressure on our body but we don't feel it. We feel it only when pressure changes e.g., when we climb a hill or travels in an airplane. Similarly, we don't feel the gravitational force or reaction from the earth. We feel the reaction force whenever it changes e.g., in free fall, in Ferris wheel, in jhoola, or in a car moving on a curved path.
Motion sickness has more to do with sensory organs. The motion of a car is quite complex. It accelerates, deaccelerate, travel on curved paths, vibrates, and so on. These lead to varying physical forces on the body. Also, the surrounding changes too fast. These effects cause motion sickness in few people, not all.
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