 Centrifugal force

 
The acceleration required to keep an object on a circular path is ω²r, where ω is the angular speed (=linear speed/r). This centripetal acceleration is directed towards the center of rotation, and the corresponding force is given by the Newtonian equation F=M⋅a. The ("ficticious") centrifugal force balances this force.
 
The centrifugal force is a ficticious force that only exists in the rotating reference frame, but it can be very useful to help understand some systems (e.g. cornering in a car, or the forces on a rotating DVD). Fill in the radius of rotation and either the linear or the angular speed (as is more convenient). The acceleration will be given (by default in units of g, but this can be changed by the menu). If you also give the object mass, then the force will also be calculated.  