Helpful Driving Information

UNDERSTANDING CENTRIFUGAL AND CENTRIPETAL FORCES

To safely negotiate curves, drivers should consider the laws of physics (the role of centripetal and centrifugal forces).

UNDERSTANDING CENTRIFUGAL AND CENTRIPETAL FORCES

If an object is moving along a curved path, the direction of its velocity is changing. The force responsible for this change in direction is called centripetal force which means center-seeking force. It is directed toward the center of the curvature. Centripetal force is necessary for an object to move with circular motion.

UNDERSTANDING CENTRIFUGAL AND CENTRIPETAL FORCES

Centrifugal force is the force that pulls out from the center on a body in circular motion. Centrifugal force is the opposite of centripetal force. Centrifugal force increases with acceleration.

UNDERSTANDING CENTRIFUGAL AND CENTRIPETAL FORCES

Have you ever twirled an object on a string around in a circle? Remember that the faster it was swung, the harder it was to hold on? That's because the force pulling against your hand was centrifugal force, which was increasing as you went faster.

UNDERSTANDING CENTRIFUGAL AND CENTRIPETAL FORCES

If a car on the "inside" lane of a curve tries to navigate with too much speed, centrifugal force will pull it away from the center and, potentially, into the path of oncoming traffic.

UNDERSTANDING CENTRIFUGAL AND CENTRIPETAL FORCES

Or, if a car is traveling with too much speed from the other direction—in the "outside" lane of a curve—centrifugal force will pull it out to the right and off the roadway.

CURVES

Because of centrifugal force, there is a strong outward pull on your vehicle. So be careful and watch out for it, especially when the road may be slippery in case of rain, mud, or snow. Sometimes a speed limit sign is not posted on a curved road. Judge how sharp the curve is. Slow down before you enter the curve. Braking on a curve may cause you to skid.

CURVES

Reduce speed before entering the curve, and slowly lighten the pressure on the brake until reaching the apex point (where the car is closest to the inside of the curve line). At the apex or exit point, apply light acceleration to pull the car out of the curve.

CURVES

Searching as far ahead as possible and identifying the existence of a curve will provide you with more time to evaluate and control the level of risk.

• Does the roadway curve to the left or right?
• Can the exit of the curve be seen ahead?
• What is the sharpness of the curve?

CURVES

• What is the lane width?
• What are the shoulder conditions?
• What is the posted speed or traffic volume?
• Is the curve on a grade, up or down hill?
• Is the field of view restricted?
• Can an apex point for exiting the curve be determined?
  

CURVES

Answering these questions and checking traffic to the rear better enables a driver to determine the best speed and lane position for negotiating a curve.

CURVES

Look for signs indicating curves. For example:
Sign 1 means that the road ahead curves right and a side road joins from the left within the curve. Be alert for vehicles entering the roadway you are traveling.
Sign 2 means that the road ahead curves right, then left.
Sign 3 means a right curve with safe speed indicator.
Sign 4 means that the road ahead winds with a series of turns or curves.