Maximum Speed of a Whirling Rock on a String - Solving a Physics Problem

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Homework Help Overview

The discussion revolves around a physics problem involving the maximum speed of a rock being whirled on a string, focusing on the tension in the string and the forces acting on the rock. The subject area includes concepts of circular motion and tension forces.

Discussion Character

  • Exploratory, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants explore the relationship between tension, mass, and speed, with one participant attempting to incorporate gravitational force into their calculations. Others question the necessity of including the gravitational term and suggest focusing solely on the tension equation.

Discussion Status

The discussion has seen participants attempting various calculations and questioning the setup of the problem. One participant has indicated a resolution to their earlier confusion regarding unit conversion, suggesting some progress in understanding.

Contextual Notes

There is mention of neglecting gravity in the problem setup, which has led to differing interpretations of the necessary equations. The tension limit of the string is also a critical constraint in the discussion.

mattmannmf
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A 630 gram rock is whirled on the end of a string 49 cm long which will break under a tension of 20 N.

a) What is the highest speed the rock can reach before the string breaks? (Neglect gravity.)
V=M/S

T- mg= ma

T-mg= m(v^2/r) solve for v

i get 2.188 m/s (which is wrong)

20-(630*9.8)= (630)(v^2/.49)

I converted 49 cm into .49 meters

help?
 
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I don't know why you have the mg term in there. I think all you need is the T=mv^2/r and solve for v.
 


20= (630)*( (v^2)/ .49)

v= .125 m/s... that was wrong when i plugged it in
 


nvm, i got it. conversion problem thanks!
 

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