Question on circular motion and Newton's laws

AI Thread Summary
When twirling a rubber stopper attached to a string, the action and reaction forces include the tension force in the string and the force exerted by the hand on the string. Circular motion exemplifies Newton's first law, as the rubber stopper maintains its motion unless acted upon by an external force. The discussion clarifies that centrifugal force is not a real force, aligning with Newton's third law, which states that for every action, there is an equal and opposite reaction. The tension force in the string corresponds to the force exerted by the hand, illustrating the interaction between the two. Understanding these force pairs is essential for grasping the principles of circular motion and Newton's laws.
excel000
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1. What are the action/reaction forces when twirling a rubber stopper attached to a string? How does circular motion illustrate Newton's first law?



2. F=ma



3. I thought about centripetal and centrifugal, but my teacher said centrifugal force isn't a real force.
 
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Your teacher of course is correct. When you talk of 'action/reaction' forces, you're talking usually about Newton's 3rd Law 'force pairs', whereby if A exerts a force on B, then B exerts a force on A that is equal in magnitude but opposite in direction to it. Does that help?
 
yea, but i can only think of the tension force, i can't think of the opposite to that. how about the force applied by the hand and the tension force?
 
excel000 said:
yea, but i can only think of the tension force, i can't think of the opposite to that. how about the force applied by the hand and the tension force?
Yes, that's one of them. If the hand pulls on the string creating a force in the string, then what can you say about the force of the string on the hand? What about the stopper/string force pair?
 

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