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Feeling Earth Spin
Name: Linda M.
Status: other
Grade: other
Location: NV
Country: N/A
Date: 1/25/2006
Question:
I understand that Earth rotates at about 1000
mph. Why do we not feel the movement of the Earth?
Replies:
Linda -
The human body is equipped to sense changes in motion, not
motion. When driving in a car - and not looking outside the windows
- it seems the same when traveling at 20 mph or 50 mph. But, the
body senses when we change speed... or direction. In reality we
change direction as the earth rotates, but it changes so slowly (360
degrees in a day) that it is beyond our ability to note. Yet if you
turn 360 degrees quickly in your car, you will sense that.
When you fly 500 mph in an airplane... does it seem fast?
Larry Krengel
Linda,
It is a good question and one of the reasons that folks thought the earth
was flat and stationary for a long time.
So what is it allows us to "feel" movement? When you are in a car, you can
see things on the road "rush" by you. When you open the window (or if you
are in a convertible) you feel the wind in your face as the car moves
through the air.
But what about when you are in an airplane? If you are high up, with no
clouds, you do not see anything rushing by...you do not feel the wind in your
face. The plane is moving faster than you car, but you do not really "feel"
like you are moving at 550 MPH.
In a like manner, as the Earth spins all of the trees, all of the buildings,
all of the people, and all of the air in the atmosphere is spinning at the
same time and at the same speed. That is why you cannot get into a
helicopter in Virginia, just hover as the Earth turns under you, and land in
California three hours later! The atmosphere turns with the earth too and
so the helicopter would get turned with the moving atmosphere and stay above
Virginia.
This is what scientists refer to as "frame of reference". A guy on the
sidewalk sees a person in a train moving by at 60 MPH. The guy in the train
sees the guy on the sidewalk moving by at 60 MPH, but the girl across the
aisle is not moving at all (relative to him and the train) because they are
both moving at 60 MPH.
I hope this helps!
Todd Clark, Office of Science
US Department of Energy
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