Eötvös effect
In the early 1900s, a German team from the Geodetic Institute of Potsdam carried out gravity measurements on moving ships in the Atlantic, Indian, and Pacific oceans.
While studying their results, the Hungarian nobleman and physicist Baron Roland von Eötvös (Loránd Eötvös) noticed that the readings were lower when the boat moved eastwards, higher when it moved westward.
In 1908, new measurements were made in the Black Sea on two ships, one moving eastward and one westward.
Geodesists use the following formula to correct for velocity relative to Earth during a gravimetric run.
Also, the moving parts of the gravimeter will be dampened, to make it less susceptible to outside influences such as vibration.
For the calculations it will be assumed that the internal weight has a mass of ten kilograms (10 kg; 10,000 g).
It will be assumed that for surveying a method of transportation is used that gives good speed while moving very smoothly: an airship.
The amount of suspension force required is the mass of the internal weight (multiplied by the acceleration of gravity) minus those 0.34 newtons.
When cruising at 10 m/s due East, the total velocity becomes 465 + 10 = 475 m/s, which requires a centripetal force of about 0.0354 newtons per kilogram.
Air masses with significant velocity with respect to the Earth have a tendency to migrate to another altitude, and when the accuracy demands are strict this must be taken into account.
The second term represents the required centripetal acceleration for the airship to follow the curvature of the Earth.
At every latitude there is precisely the amount of centripetal force that is necessary to maintain an even thickness of the atmospheric layer.
The situation is comparable to a racecar on a banked circuit with an extremely slippery road surface.
If the airship has a westward velocity then the situation is like that of a racecar on a banked circuit going too slow: on a slippery surface the car will slump down.
