A Moment Please: Help MiYu with the Test Question

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In summary, the conversation discusses a physics question about a winch and its pegs. It is explained that the pegs are fixed in place and when a force is applied, they exert an equal and opposite force. The net force is determined to be 0 and the torques are balanced. Using equations, it is found that R1 = 2100 and R2 = 1900. The original poster thanks the person who clarified the question.
  • #1
Miyu
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A "moment" please...

Hello everyone!

Well, I found this moment question in a test paper...so if you know how to answer it please do help me clarify my doubts!


Pls visit:
http://sg.geocities.com/be_do_get/Qn3a.doc [Broken]

It takes a while to load, so be patient!

Thank you!

Love, MiYu.
 
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  • #2


The pegs are fixed relative to the winch. When a force (effort) is applied, the handle bar pushes against peg A to the left, so peg A exerts an opposite and equal force to the right (Newton's third law). Similarly, the handle bar pushes against peg B to the right, so peg B exerts an opposite and equal force to the left. R1 and R2 are in opposite directions because one is above the center of the winch while the other is below the center of the winch.

The center of the winch does not undergo any translational motion.
Hence the net force is 0. 200+R2-R1 = 0.

Also balance the torques (i.e., the "moments") since there is no rotation about the center of the winch unless the exerted force > 200. Let torques that point out of the page be +, and those that point into the page be -.
200*40-R1*2-R2*2 = 0.



Solve[{200 + R2 - R1 == 0, 200*40 - R1*2 - R2*2 == 0}, {R1, R2}]{{R1 -> 2100, R2 -> 1900}}
Solving these two equations (on Mathematica), I get R1 = 2100 and R2 = 1900.

Hope this helps!
--Ying
 
  • #3
Gee thanks! I've understood! ^^
 

1. What is "A Moment Please: Help MiYu with the Test Question" about?

"A Moment Please: Help MiYu with the Test Question" is a short story about a young girl named MiYu who is struggling with a test question. She asks for a moment to think, and her friend helps her come up with a solution.

2. Who is the main character in "A Moment Please: Help MiYu with the Test Question"?

The main character in this story is MiYu, a young student who is facing a difficult test question.

3. What is the lesson or theme of "A Moment Please: Help MiYu with the Test Question"?

The lesson of this story is to never be afraid to ask for help and to always have patience and perseverance when facing challenges.

4. Is "A Moment Please: Help MiYu with the Test Question" based on a true story?

No, "A Moment Please: Help MiYu with the Test Question" is a work of fiction.

5. What age group is "A Moment Please: Help MiYu with the Test Question" suitable for?

This story is suitable for all ages, but it may resonate more with young readers who are facing academic challenges or learning how to ask for help.

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