Accordingly with Newton's second law, , if there is an acceleration, there is a net force acting on the object. This force has the same direction as the direction of the acceleration. Therefore, for the case of centripetal acceleration, there is an equivalent force directed to the center of the circle called the centripetal force, , this force is given by

Centripetal Force Magnitude
Direction Toward the center of the circle.

In order to express this result, it is necessary to assign a mass to the point P moving in uniform circular motion (magnitude of the velocity is unchanged). This mass is .

 

This result is key in understanding situations where mobiles moves in uniform circular motion. In those cases, the following reasoning should help to determine the forces acting on the object,

  1. If the object is moving in circular motion, there is a centripetal acceleration.
  2. if there is a centripetal acceleration, at lease one of the forces should be the centripetal force. A centripetal force should always point toward the center of the circle.
  3. If a force is determined to always point toward the center, then the motion of the object is circular motion.

 

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Example

 

  1) Question

 

a)

-19.3 KJ

 

b)

1028.8m and 0.69g

 N

c)

13333.3m and 069g

 

d)

-29.5 KJ

 

e)

None of the above.

 

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by Luis F. Sez, Ph. D.    Comments and Suggestions: LSaez@dallaswinwin.com