Circular motion vertical force

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Discussion Overview

The discussion revolves around the forces acting on an object in horizontal circular motion, particularly focusing on the role of tension and gravity. Participants explore the conditions under which an object can maintain such motion and the implications of the angle of the string with respect to the vertical axis.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions the assumption that the angle with the vertical axis can be 90°, suggesting that it may need to be less than that for the object to remain in circular motion.
  • Another participant asserts that if the string were completely horizontal, there would be no vertical component of force, which raises concerns about the object's ability to remain in motion under gravity.
  • A further contribution clarifies that if the object is on horizontal ground, the normal force would compensate for the weight, but if it is above ground with no other forces acting, the string cannot be horizontal.

Areas of Agreement / Disagreement

Participants express differing views on the feasibility of maintaining horizontal circular motion with a completely horizontal string. There is no consensus on the implications of the angle of the string or the forces involved.

Contextual Notes

The discussion highlights assumptions about the forces acting on the object and the conditions necessary for maintaining horizontal circular motion, but these assumptions remain unresolved.

ramanakumars
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Hi everyone,
If you have a horizontal circular motion (with gravity action on the object), what holds the object up in the horizontal plane? All vertical components of the tension go to zero when the angle with the vertical axis is 90°... Where am I going wrong?

Thanks

Ramana
 
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Why would the angle with the vertical axis be 90° rather than something a bit less than that?
 
Do you mean to say that even theoretically, you cannot have an object in uniform circular motion completely with the attached string completely horizontal?
 
ramanakumars said:
Do you mean to say that even theoretically, you cannot have an object in uniform circular motion completely with the attached string completely horizontal?
Right. For the reason that you are pointing out. If the string were horizontal, there would be no vertical component of force.
 
ramanakumars said:
Do you mean to say that even theoretically, you cannot have an object in uniform circular motion completely with the attached string completely horizontal?

In that case, the force the string exerts on the body is horizontal, so there must be another force that compensates the weight force. If the body is doing its horizontal uniform circular motion sliding on horizantal ground, then it is the normal (support) force that compensates the weight.

If the body is doing its horizontal uniform circular motion above ground, and there is no other force acting on the body (just the weight and the tension of the string), then the string can not be totally horizontal.
 
I see... Thanks for clearing that up guys! Makes perfect sense!
 

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