If the earth is spinning and in orbit, why don't we feel it in our everyday life?
(Lansing State Journal, June 21, 1995)
The reason we don't feel it can be explained by thinking of an airplane ride. Imagine we are in a perfect airplane. That is, an airplane that is flying at a constant velocity without slowing down, speeding up, turbulence or turning.
In this airplane, we are free to move about without noticing that the plane is moving. We can run, walk, play catch and do anything that we can do on the ground because we are moving at the same constant velocity as the airplane. In fact, if the windows were closed, there is no way we could tell whether we were flying along at this constant velocity or whether we were sitting motionless on the runway.
If, however, the pilot decides to speed up, slow down, or turn, the plane undergoes an acceleration and we can feel an inertial force.
Think of making a fast left turn in a car. You feel an inertial force pushing you to the right as a result of your frame or reference (in this case the car) undergoing an acceleration (the sharp left turn).
Like the plane, our solar system is moving very close to a constant velocity. So, just as in the plane, we can't feel that we are moving through space. Although the Earth is moving in a curved path around the sun, which means it is undergoing an acceleration, the inertial force is so small that we don't feel it.
We can however measure an inertial force caused by the earth's rotation. This force is called the Coreolis force and it plays an important role in our climate and weather planes.