Why does a stone tied to a string not fall?

  • Context: Undergrad 
  • Thread starter Thread starter utkarsh5
  • Start date Start date
  • Tags Tags
    Fall String
Click For Summary

Discussion Overview

The discussion revolves around the mechanics of a stone tied to a string that is spun in a horizontal circle, specifically addressing why the stone does not fall despite the gravitational force acting on it. The scope includes conceptual understanding and technical explanations of forces involved in circular motion.

Discussion Character

  • Conceptual clarification
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions why the stone does not fall when spun, noting that the vertical component of acceleration should not be affected by horizontal velocity or centripetal force.
  • Another participant suggests that the gravitational force is balanced by the centripetal force, preventing the stone from falling.
  • It is proposed that the string cannot be completely horizontal and is instead at an angle, with the vertical component of tension balancing the stone's weight in a steady state.
  • A further clarification emphasizes that when the stone moves in a horizontal circle, the string pulls at an angle, supporting the stone's weight and providing the necessary centripetal force, resulting in zero vertical acceleration.
  • One participant expresses gratitude for the explanations, indicating a better understanding of the concept.

Areas of Agreement / Disagreement

While some participants agree on the mechanics of the forces involved, there is still some ambiguity regarding the conditions under which the stone maintains its height during circular motion. The discussion does not reach a definitive consensus on all aspects of the question.

Contextual Notes

The discussion does not resolve the nuances of how the forces interact in different scenarios, such as varying speeds or angles of the string, which may affect the stone's motion.

utkarsh5
Messages
23
Reaction score
0
when we tie a stone to a string and spin it,it does not seem to fall.why does it happen?i mean to say that,no matter how great its horizontal velocity and centripetal force is,the vertical component of the acceleration won't be affected.it means that the stone should keep falling no matter how hard it is spun.why does it happen then?
 
Physics news on Phys.org
Here the falling force (gravitational) is being balanced by centripetal force. Hence do not fall.
 
The string can never be completely horizontal, instead it's at some angle, and the vertical component of tension equals the weight of the stone (assuming steady state). It might be easier to understand this if you imagine that the stone is moving slowly, with the string nearly vertical, following the shape of a cone as the stone moves in a horizontal circle.
 
rcgldr said:
The string can never be completely horizontal, instead it's at some angle, and the vertical component of tension equals the weight of the stone (assuming steady state). It might be easier to understand this if you imagine that the stone is moving slowly, with the string nearly vertical, following the shape of a cone as the stone moves in a horizontal circle.

rcgldr, you are right
but, utkarsh5 is asking about
when the stone is spinning in a horizontal circle why doesn't it fall, means what makes the stone to gain height.
 
asitiaf said:
rcgldr, you are right
but, utkarsh5 is asking about
when the stone is spinning in a horizontal circle why doesn't it fall, means what makes the stone to gain height.
rcgldr gave the right answer. When the stone is making a horizontal circle, the string pulls at an angle, supporting the stone's weight as well as providing the centripetal force. The vertical acceleration of the stone is zero.
 
thank you for your answers!now i understand the concept!thank you!
 

Similar threads

  • · Replies 60 ·
3
Replies
60
Views
6K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 8 ·
Replies
8
Views
2K
Replies
12
Views
4K
  • · Replies 14 ·
Replies
14
Views
2K
  • · Replies 16 ·
Replies
16
Views
3K
  • · Replies 11 ·
Replies
11
Views
3K
  • · Replies 47 ·
2
Replies
47
Views
5K
  • · Replies 0 ·
Replies
0
Views
1K
  • · Replies 3 ·
Replies
3
Views
1K