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(this is a homework question)

To this, I would say that the centrifugal force is just the reactionary force of the centripetal force, which is causing the hammer to 'want' to move away.

Therefore, I would say that there is always a centrifugal force as it is just a reactionary force to centripetal force (even though its fictitious)

Basically, I want to know if this was correct. I have done some other reading, and I was wondering if the centrifugal force was instead caused by the tension on the string when the athlete was swinging the hammer around?

Qmechanic
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Hugh Martini
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  • Hi Hugh, and welcome to Physics Stack Exchange! It seems that you have an answer already, so what is it that you want to ask? – David Z Mar 22 '15 at 11:50
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    @David Z : I cant understand how this is a homework question. – Paul Mar 22 '15 at 11:55
  • How does he experience the centrifugal force? What object applies that force on him? – Hugh Martini Mar 22 '15 at 11:58
  • @Paul because the question starts off by saying "(this is a homework question)". I also could have closed it (the first version, prior to the edit) as "unclear what you're asking". – David Z Mar 22 '15 at 11:59
  • @HughMartini The string tension is the centripetal force, yes. It points towards the center of the circular motion. As you say, the centrifugal force is non-existant. It is simply the feeling you have, when you are dragged by the centripetal force the opposite way - your body wants to stay where it is (because of its mass / inertia). – Steeven Mar 22 '15 at 12:04
  • So in relation to he question, there is always a centrifugal force associated with a centripetal force then? – Hugh Martini Mar 22 '15 at 12:07
  • It's a shame this has been closed because I think you have put your finger on an important point. The head of the hammer is not moving in a straight line at constant speed, so we know from Newton's first law that there must be a force acting on it. Likewise the hammer thrower is not moving ina straight line at constant speed, so there must be a force acting on them. These are real forces - there is nothing fictitious about them. The force is, as you say, being produced by the string. To see this imagine suddenly removing the string, at which point the head of the hammer and the thrower ... – John Rennie Mar 22 '15 at 15:07
  • ... would both start moving in a straight line at constant speed. So the centripetal force is the force the string produces on the hammer head, and the centrifugal force is the force the string produces on the thrower. – John Rennie Mar 22 '15 at 15:08
  • You ask there is always a centrifugal force associated with a centripetal force. Well the string isn't going anywhere, so the net force on the string must be zero. That means the centripetal force the string produces on the hammer head must be equal and opposite to the centrifugal force the string produces on the thrower. So yes, in this case there is an equal and opposite centrifugal force associated with the centripetal force. – John Rennie Mar 22 '15 at 15:10
  • http://physics.stackexchange.com/questions/93599/do-centripetal-and-reactive-centrifugal-forces-cancel-each-other-out/93637#93637 – mmesser314 Mar 22 '15 at 15:44

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