# 200 Proof: Relative Velocity…again

25) If Earth and its atmosphere were constantly spinning eastwards over 1000mph, then the average commercial airliner traveling 500mph should never be able to reach its Eastward destinations before they come speeding up from behind! Likewise Westward destinations should be arrived at thrice the speed, but this is not the case.

I addressed this before in one manner or another. It is described in greater detail by NASA. Essentially, once a person chooses a reference frame, that reference frame must be the same throughout the thought experiment. A ball thrown 10 miles per hour forward from a 60 mph car will hit a target at 70 miles per hour. In this case the reference frame is the car. If you selected the car as the reference frame, the person throws a ball forward at 10 mph from a car sitting at rest with a target moving at the car at 60 mph.

In the above scenario. The plane stationary plane is moving eastward on Earth’s surface at 1000 mph. It takes off and travels eastward at 500 mph; in the author’s logic, suddenly the Earth’s surface becomes stationary for this measurement. Lastly, the destination begins moving again at 1000 mph eastward.

The error is that the relative velocity of the flying plane is 1500 mph. The plane adds 500 mph to its 1000 mph initial velocity to take off and reach cruising altitude.