How Do You Calculate the Weight of a Pumpkin Suspended by Two Scales?

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Homework Help Overview

The discussion revolves around calculating the weight of a pumpkin suspended by two scales, with specific readings from each scale and an angle between the strings. The problem involves concepts from physics related to forces and vector addition.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the use of the law of cosines and vector addition to determine angles and components of forces. There are questions about the necessity of finding angles and whether the method described is appropriate for the problem.

Discussion Status

Some participants are exploring different interpretations of the problem, particularly regarding the application of the cosine law and vector addition. There is a request for clarification on the original poster's method and an invitation to share more detailed work.

Contextual Notes

Participants acknowledge that this is a homework problem and express concern about the appropriateness of the methods being used. There is a suggestion that the original poster should consider posting in a dedicated homework section.

jeetp26
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Find the weight of a pumpkin hanging from two scales, if scale one reads 33 N, scale two reads 49 N, and the angle θ between the strings coming from the two scales is 131 degrees.
[URL]http://a1.educog.com/res/msu/plough/physlibrary/graphics/pumpkin.gif[/URL]

I attempted to do this. I used law of cosines to find the other two angles and then i found both Y-components of scale 1 and scale 2. Then i added them. And I'm pretty sure that's the method to do it. And yet, when I enter it into the computer, it says "wrong answer".

Any help?
 
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jeetp26 said:
Find the weight of a pumpkin hanging from two scales, if scale one reads 33 N, scale two reads 49 N, and the angle θ between the strings coming from the two scales is 131 degrees.
[URL]http://a1.educog.com/res/msu/plough/physlibrary/graphics/pumpkin.gif[/URL]

I attempted to do this. I used law of cosines to find the other two angles and then i found both Y-components of scale 1 and scale 2. Then i added them. And I'm pretty sure that's the method to do it. And yet, when I enter it into the computer, it says "wrong answer".

Any help?

Finding the individual angles is possible but quite tedious. I don't quite see what you mean when you claim that you found them from the cosine law.
If by "cosine law" you mean the vector addition formula, then you don't need to find the angles and you don't need to add components. Maybe you can show some work. This looks like homework.
 
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nasu said:
Finding the individual angles is possible but quite tedious. I don't quite see what you mean when you claim that you found them from the cosine law.
If by "cosine law" you mean the vector addition formula, then you don't need to find the angles and you don't need to add components. Maybe you can show some work. This looks like homework.

Yes it is a homework problem. Don't get the idea that I'm trying to get people to do my homework for me. Haha.

Below are the law of cosines:

[PLAIN]http://www.ies.co.jp/math/java/trig/yogen1/yogen-moji.gif
 
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Then why don't you post it in the homework section?

Regarding the cosine law, I still don't see how you calculate the "other two angles" but it does not matter.
Do you know how to use it to find the resultant (sum) of two vectors when you know their magnitudes and the angles between them? The two forces here are the tensions in the wires.
What is the relationship between the vector sum of the two tensions and the weight?
 

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