Spacetime

Coriolis' Force


Coriolis' Force

This is indeed an elementary point for physics students, but for philosophy students, this is a good illustration of "inertial force", which has been discussed so often in our readings.

If a mass point m moves with velocity v on a revolving system (with angular velocity °… relative to the inertial frame), the mass will receive an inertial force (in the revolving system) 2mv°…sin°®, in the direction indicated in the figure; this is Coriolis' force. Such forces are sometimes called "apparent forces", but this is misleading (according to my philosophical taste). G.G. de Coriolis (1792-1843) is a French physicist.

Coriolis' force can be observed on the earth, for instance, since the earth is a revolving system; if you drop an object from a high tower, it will drop a little to the east from the intersection of the vertical line and the surface.

Another example is Foucault's pendulum; this pendulum shows that the earth is rotating, because the direction of oscilation gradually changes on the earth. This change is due to Coriolis' force. J.B.L. Foucault (1819-1868), French experimental physicist, he demonstrated his pendulum in 1851.


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Last modified March 27, 2003. (c) Soshichi Uchii

suchii@bun.kyoto-u.ac.jp