Centripetal, << sehn TRIHP uh tuhl, >> force, is the force that compels a body to move in a circular path. According to the law of inertia, in the absence of forces, an object moves in a straight line at a constant speed. A force must act on an object to make it move in a curved path. When you whirl a stone around on a string, you must pull on the string to keep the stone from flying off in a straight line. The force the string applies to the object is the centripetal force. The word centripetal is from two Latin words meaning to seek the center.
Centripetal force acts in other situations. For example, a speeding automobile tends to move in a straight line. Centripetal force must act on the car to make it travel around a curve. This force comes from the friction between the tires and the pavement. Centripetal force also enables Earth to travel in its nearly circular orbit around the sun. The gravitational pull of the sun on Earth provides the centripetal force.
You can use the following formula to calculate the centripetal force, F, necessary to make an object travel in a circular path: F equals m times v-squared divided by r.
Multiply the object’s mass, m, by the square of its velocity (the velocity multiplied by itself), v-squared, and divide this product by the radius of the circle in which the object moves, r. In the metric system, the centripetal force is given in newtons when the object’s mass is expressed in kilograms, the velocity in meters per second, and the radius in meters.
