Tuesday, April 7, 2009
The human body can sense changes due to motion but not the motion itself.
When a flight is traveling at a high speed and altitude (say 800 mph and 30000 feet) you do not really feel like you are moving.
You don't see any changes also because there are no clouds at this altitude.
When you are in a car traveling at 50mph, you can see things on the road rush by you.
When you open the window you feel the wind in your face as the car moves.
These are the changes that you can feel due to motion but still you cannot feel the motion.
If you close all the windows and close your eyes, you'll feel like just sitting in your seat without going anywhere.
You would feel the changes when you change the speed (from 40mph to 80 mph) or change the direction (take a U turn).
The Earth always spins at the same speed (about 1000 mph or 2200 kph) so we don’t see any changes due to change in speed.
The Earth rotates in same direction (360 degrees) in a day.
But this occurs very slowly that it is beyond our ability to observe this rotation.
It’s like making a big 360 degree turn in 1 hour in your car instead of a quick U turn.
As the Earth spins, all objects (trees, buildings, people and air) are spinning at the same time and at the same speed.
This happens because the Earth pulls everything to itself. This pull is called gravity.
Gravity is not just the attraction between objects and the Earth.
It is an attraction that exists between all objects, everywhere in the universe.
For this exact reason you cannot get into a helicopter in Asia, just stay in the same place as the Earth spins, and land in Europe eight hours later.
Since all objects are spinning at the same time and at the same speed we don’t see any changes.
For example, a girl on the sidewalk sees a person in a train moving by at 90 MPH.
The girl in the train sees that girl on the sidewalk moving by at 90 MPH.
But the girl across her seat is not moving at all because they are both moving at 90 MPH.