MOMENT OF INERTIA

This is similar to inertia except that it relates to rotating movement rather than linear movement. Linear movement is the tendency of an object to remain motionless if at rest and to keep moving in a straight line if already in motion. The moment of inertia, however, is the tendency of an object to resist being accelerated when it is rotating. The polar moment of inertia is the rotating movement around a vertical axis through the center of rotation. It greatly affects steering and handling response in an automobile. The greater the length of the axis the greater the polar moment of inertia. By having the heavy components of a vehicle such as the engine and transmission between the two front wheels, the polar moment of inertia is low so that the tires can easily change the direction of the vehicle.