Resolving forces: Mass on a string

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Homework Help Overview

The problem involves a mass of 50 grams hanging in equilibrium on a string, which is pulled aside by a force of 0.3N at an angle of 30° with the horizontal. The goal is to determine the angle the string makes with the vertical and the tension in the string.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to understand the angle the string makes with the vertical, questioning why it is not 60° based on the relationship between the angles. They also express confusion regarding the tension in the string, noting discrepancies in their calculations from horizontal and vertical force resolutions.
  • Some participants suggest considering the implications of the mass's weight and the applied force on the string's angle and tension.
  • Others question the relevance of the thread title, noting a potential error regarding the mention of a spring.
  • One participant prompts the original poster to consider drawing a free body diagram to visualize the forces acting on the mass.

Discussion Status

Contextual Notes

Participants are navigating the complexities of equilibrium conditions and the relationships between the applied force, tension, and gravitational force. There is an acknowledgment of the need for clarity on the problem setup and potential corrections to the thread title.

thebosonbreaker
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Homework Statement


A mass of 50 grams hangs in equilibrium on a string. The mass is pulled aside and upwards by a force of 0.3N which makes an angle of 30° with the horizontal. Find the angle that the string makes with the vertical and the tension in the string.

Homework Equations


Body is in equilibrium, so I will need to resolve forces (tension and weight).

The Attempt at a Solution


For the first part of the question (find the angle that the string makes with the vertical):
I do not understand why this is not 60° - the string will move in the same direction as the 0.3N force applied to it, so if it makes an angle of 30° with the horizontal (the angle between 'horizontal'/'vertical' being a right angle), the angle made with the vertical must be: 180 - (90 + 30) = 60°. Could somebody please explain why this is not the case and how to find the angle?

For the second part of the question (finding the tension in the string):
Resolving horizontally I have that: Tcos30° = 0.3 [the horizontal component of tension equals the horizontal force applied]
Resolving vertically I have that: Tsin30° = mg = 0.05g
These both lead to different answers for T.

Could somebody clraify this problem? I'm having a bit of a hard time with it.
Thanks a lot in advance, your help will be greatly appreciated!
 
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thebosonbreaker said:

Homework Statement


A mass of 50 grams hangs in equilibrium on a string. The mass is pulled aside and upwards by a force of 0.3N which makes an angle of 30° with the horizontal. Find the angle that the string makes with the vertical and the tension in the string.

Homework Equations


Body is in equilibrium, so I will need to resolve forces (tension and weight).

The Attempt at a Solution


For the first part of the question (find the angle that the string makes with the vertical):
I do not understand why this is not 60° - the string will move in the same direction as the 0.3N force applied to it, so if it makes an angle of 30° with the horizontal (the angle between 'horizontal'/'vertical' being a right angle), the angle made with the vertical must be: 180 - (90 + 30) = 60°. Could somebody please explain why this is not the case and how to find the angle?

For the second part of the question (finding the tension in the string):
Resolving horizontally I have that: Tcos30° = 0.3 [the horizontal component of tension equals the horizontal force applied]
Resolving vertically I have that: Tsin30° = mg = 0.05g
These both lead to different answers for T.

Could somebody clraify this problem? I'm having a bit of a hard time with it.
Thanks a lot in advance, your help will be greatly appreciated!
In equilibrium, the string aligns in the direction of the resultant of gravity and the applied force.
 
If the object were heavy enough the applied force might only move it a very short distance. No where near 60 degrees.
 
The thread title mentions a spring. I don't see any mention of a spring in the problem itself. o_O

Edit: Does the thread title need correction?
 
Have you drawn a free body disgram showing the forces acting on the mass, or do you feel like you have advanced beyond the point where you need to use free body diagrams?
 

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