Tension and Newton's second law

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Homework Help Overview

The problem involves a 7kg mass suspended from a massless string, released from rest at an angle of 18 degrees from the vertical. The discussion centers around analyzing the forces acting on the mass, particularly tension and gravitational force, and understanding the dynamics of the system as it begins to move.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss the free body diagram and the forces acting on the mass, questioning the assumptions about acceleration at the moment of release. There is also inquiry into the direction and role of tension in the system.

Discussion Status

The discussion is active, with participants exploring different interpretations of the forces involved. Some guidance has been offered regarding the free body diagram, but there is no explicit consensus on the assumptions being made about the motion of the mass.

Contextual Notes

There are questions about the initial conditions of the mass and the implications of assuming it is at rest at the moment of release, as well as the relationship between tension and gravitational force in the context of the problem.

Touran Khan
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Homework Statement


A 7kg mass is hung from a 1.5 m long massless string. It is released from rest with the string displaced by
an angle of 18 degrees from vertical.
a) Make a free body diagram of the forces on the mass just after it is released.
b) Find the tension in the string.
c) Find the initial acceleration of the mass.

Homework Equations


F = ma

The Attempt at a Solution



b) Fy: Tcos18 - 68.6 = ma

Does ay = 0? And if it does then why exactly? Is it just cause they want the tension at that point so the object is not assumed to be moving?

However there will be an ax value right?

Thanks.
 
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In which direction does the tension act just after the mass is released? (What is the string actually accomplishing in this system?)
 
olivermsun said:
In which direction does the tension act just after the mass is released? (What is the string actually accomplishing in this system?)
 

Attachments

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That is the diagram I made. Tension and Fg are in opposite directions which is how I got Tcos18 - 68.6 = ma
 
According to your diagram, Tension and Fg are not exactly in opposite directions. Just kind of.
 

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