There is such a thing as centrifugal force
, but it's a misnomer
isn't a force at all. Rather, it's a math
introduced by physicist
s when they want to use
's laws of motion
in a rotating, non-inertial reference
. Newtonian mechanic
s is only valid in frames of reference that
are either stationary
or moving with constant velocity
theory, there's no difference between the two anyway).
Imagine a marble
on a rotating platform on a table. In attempting to
describe this situation, one traditionally chooses a coordinate axis
attached to the table, which is not accellerating, and compares the
with the centripetal force
between the marble and the platform to determine where the
marble will go. Unfortunately, this can be conceptually difficult. The
alternative, often discouraged in introductory physics
allowed later on, is to choose a coordinate axis
rotating relative to
the table, and attached to the platform. Newton's classic equation
will not work
in this reference frame because it is
accellerating, but they can be made to work
by treating it as if
it weren't. To do this we have to introducing a virtual
outward-pointing force, the centrifugal force. A derivation
centrifugal force using vector calculus
Newton's Second Law in an inertial reference frame.
Apply this coordinate transformation...
Vi=Vr+(w x r)
...to the radius vector.
Vr)+(w x (w x r))
...to the velocity vector.
Fi-2m(w x Vr)-m(w x
(w x r))=mAr
Substitute into the initial Second Law equation...
Vr)-m(w x (w x r))
...and get the effective force.
The third term on the right, -m(w x (w x r)) is the
The second term on the right is the icing on the cake. -2m(w x
Vr) is the Coriolis force.