Lateral Acceleration.

Lateral acceleration is the measurement of the vehicles ability to corner. What we feel during a corner is that a force pushes the vehicle and its occupants to the outside of a turn. In reality, as both the car and occupants turn, the people inside are still subject to Newton’s First Law of Motion and continue to move in a straight line. The effect is that we feel pushed toward the outside of the corner. Centripetal force, meaning “toward the center,” is the force that pulls an object toward the center of a circle as the object rotates. Imagine swinging a ball over your head and that the ball is attached to a string. The ball travels in a circle because the centripetal force is pulling the ball toward the center. Obviously, cars do not have strings pulling them in toward the center of a circle while turning but they do have tires. The tires are exerting the force toward the center. The lateral (sideways) force is perpendicular to the direction the car is traveling. This is where the term lateral acceleration comes from for vehicle test scores. The test is performed by driving the car on a large test-track circle at ever-increasing speeds. The faster the car can go around the circle, the greater the lateral acceleration. This means the better the vehicle will handle when cornering. Figure 6-12 shows an illustration of how this test is performed. Low riding, wide wheelbase sports cars can achieve a much higher lateral acceleration than a vehicle that is higher off the ground, such as a minivan or SUV.