What is the Tension in a String Holding a Ball in Motion?

  • Thread starter Thread starter codz30
  • Start date Start date
  • Tags Tags
    Motion Tension
Click For Summary

Homework Help Overview

The discussion revolves around a physics problem involving a ball of mass m attached to a string, which is released from a horizontal position. The objective is to analyze the forces acting on the ball as it swings through the lowest point of its motion, specifically focusing on the tension in the string and its relationship to the weight of the ball.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to relate centripetal force to the tension in the string, questioning how the equation might lead to the conclusion that the tension equals three times the weight of the ball. Some participants suggest considering the kinetic energy at the lowest point and the forces involved, while others seek clarification on the terminology used regarding the "magnitude" of the string's tension.

Discussion Status

The discussion is active, with participants exploring different interpretations of the problem and questioning the clarity of the original statement. Some guidance has been offered regarding the relationship between kinetic energy and forces, but there is no explicit consensus on the interpretation of the tension in the string.

Contextual Notes

Participants are grappling with the definitions and implications of the terms used in the problem statement, particularly regarding the concept of tension and its relationship to the forces acting on the ball.

codz30
Messages
2
Reaction score
0

Homework Statement


A ball of mass m on the end of a string is released from rest when the string is held horizontal
eg:
0-----

Prove that as the ball moves through the lowest point in its swing the string has a magnitude equal to three times the weight of the ball.

Homework Equations


Fc = mv^2/r
Weight = mg

The Attempt at a Solution


Because its motion in a vertical circular plane, I thought that mv^2/r would be needed, obviously the equation would end up something like
xxxxxx = 3mg
But I'm not sure how or why that would happen?
Any thoughts?
 
Physics news on Phys.org
Welcome to PF.

Consider what the kinetic energy is of the ball at the lowest point.

Using your knowledge of centripetal acceleration and the weight then what is the force on the string at that point?
 
What does it mean to say, "...the string has a magnitude equal to three times the weight of the ball"? How does the string have a magnitude?
 
Dr.D said:
What does it mean to say, "...the string has a magnitude equal to three times the weight of the ball"? How does the string have a magnitude?

I'm sure they intend the "tension in the string" ...
 
The point is, it would really help if people asking questions would learn to ask those questions.
 

Similar threads

  • · Replies 3 ·
Replies
3
Views
1K
Replies
8
Views
2K
Replies
19
Views
4K
  • · Replies 5 ·
Replies
5
Views
2K
Replies
21
Views
2K
  • · Replies 2 ·
Replies
2
Views
1K
  • · Replies 7 ·
Replies
7
Views
5K
  • · Replies 3 ·
Replies
3
Views
1K
  • · Replies 10 ·
Replies
10
Views
11K
Replies
27
Views
4K