Finding Forces & Work: 105 kg Mass Suspended by 7 m Rope

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Homework Help Overview

The problem involves a 105 kg mass suspended by a vertical rope of 7 m, with a focus on determining the horizontal force required to hold the mass displaced 3 m sideways and the work done in moving it to that position. The context includes gravitational acceleration set at 9.80 m/s².

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants discuss the calculation of angles and tension in the rope, with some questioning the assumptions made about the tension when the bag is displaced. There are inquiries about how to calculate the work done based on the weight and displacement of the bag.

Discussion Status

Some participants have provided guidance on calculating the tension while the bag is displaced and suggested using the weight and angle for further calculations. There appears to be a productive exploration of the problem, with various interpretations being considered.

Contextual Notes

Participants note the need to calculate tension under displacement conditions and clarify the distinction between initial calculations and the requirements of the problem. There is an acknowledgment of potential errors in earlier calculations without definitive resolutions.

honeyspells
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::A mail bag with a mass of 105 kg is suspended by a vertical rope of length 7.00 m .

A) What horizontal force is necessary to hold the bag in a position displaced sideways a distance 3.00 m from its initial position?
Take free fall acceleration to be g = 9.80 m/s2 .

B) How much work is done by the worker in moving the bag to this position?
Take free fall acceleration to be g = 9.80 m/s2 .

m= 105 kg
y= 7 m
x= 3 m
So first I made a right triangle to find the angles, the angles I found were 25(from the vertical) and 66.

The tension in the string is 105 kg x 9.8 m/s2 right? with that I have T=1029 N

I then used 1029tan(25)= 479 N .What do I need to do to figure out ho much work is done?
tips for moving on?
 
Last edited:
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Work is the integral of the working force over the arc length through which it acts. Have you tried calculating that?
 
honeyspells said:
::A mail bag with a mass of 105 kg is suspended by a vertical rope of length 7.00 m .

A) What horizontal force is necessary to hold the bag in a position displaced sideways a distance 3.00 m from its initial position?
Take free fall acceleration to be g = 9.80 m/s2 .

B) How much work is done by the worker in moving the bag to this position?
Take free fall acceleration to be g = 9.80 m/s2 .

m= 105 kg
y= 7 m
x= 3 m
So first I made a right triangle to find the angles, the angles I found were 25(from the vertical) and 66.

The tension in the string is 105 kg x 9.8 m/s2 right? with that I have T=1029 N

I then used 1029tan(25)= 479 N .What do I need to do to figure out ho much work is done?
tips for moving on?
For work just take the weight of the object multiplied by its displacement, you'll probably need the angle you calculated above. Also, I think your above calculations are incorrect...
edit: not incorrect, just not what the problem is asking for
 
Last edited:
you calculated the tension if the bag was just hanging vertically, I believe you need to calculate tension while the bag is displaced...
 
Ok, after doing this problem it looks like you are on the right track (you've calculated the weight and the angle to the vertical). Your next step will be to use the weight and angle to calculate the tension in the rope, then use this tension (and angle) to calculate the force needed to hold the bag a certain distance from the vertical.
 

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