Centripetal Force

From Wind wiki

In physics, the centrifugal force is an outward force associated with rotation. The centrifugal force is actually one half of the action-reaction pair that is coupled with the centripetal force. According to Newton's first law of motion, a moving body travels along a straight path with constant speed (i.e., has constant velocity) unless it is acted on by an outside force. For circular motion to occur there must be a constant force acting on a body, pushing it toward the center of the circular path. This force is the centripetal (“center-seeking”) force. For a planet orbiting the sun, the force is gravitational; for an object twirled on a string, the force is mechanical; for an electron orbiting an atom, it is electrical. The magnitude F of the centripetal force is equal to the mass m of the body times its velocity squared v 2 divided by the radius r of its path: F=mv2/r. According to Newton's third law of motion, for every action there is an equal and opposite reaction. The centripetal force, the action, is balanced by a reaction force, the centrifugal (“center-fleeing”) force. The two forces are equal in magnitude and opposite in direction. The centrifugal force does not act on the body in motion; the only force acting on the body in motion is the centripetal force. The centrifugal force acts on the source of the centripetal force to displace it radially from the center of the path. Thus, in twirling a mass on a string, the centripetal force transmitted by the string pulls in on the mass to keep it in its circular path, while the centrifugal force transmitted by the string pulls outward on its point of attachment at the center of the path. The centrifugal force is often mistakenly thought to cause a body to fly out of its circular path when it is released; rather, it is the removal of the centripetal force that allows the body to travel in a straight line as required by Newton's first law. If there were in fact a force acting to force the body out of its circular path, its path when released would not be the straight tangential course that is always observed.

In relation to how the centrifugal force affects the wind, imagine air moving from a high- to a low-pressure area. Initially, the Pressure Gradient Force will cause the air to move in a straight line toward the low-pressure core at a particular speed as determined by the pressure gradient. But as soon as the air begins moving, the Coriolis Effect will cause it to curve to the right (in the northern hemisphere) with the amount proportional to the speed and latitude of the moving air. At that point, the trajectory shows curvature, and the centrifugal force will begin altering the trajectory by pulling the air to the outside of the curve. The faster the wind movement and the tighter the curve, the greater the centrifugal pull. An air stream will initially have its trajectory altered first by the Coriolis effect and then again by the centrifugal force.

Mathematically, the centrifugal force can be expressed as:

Fcfg=v2/r

, where v is the linear wind velocity and r represents the radius of curvature of motion. For perfectly straight flow, r would be infinite and the centrifugal force would approach zero. The tighter the curvature (smaller radius) and the faster the winds, the larger the centrifugal force will be. <math>Insert formula here</math>