Quick question about resolving force

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Discussion Overview

The discussion revolves around the resolution of a force into its y-components, particularly in the context of a force acting perpendicular to a slope. Participants are examining the correct method for calculating these components using trigonometric functions and geometry.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant expresses confusion about resolving a force into its components and seeks clarification on their approach.
  • Another participant suggests that the angle of the force relative to the horizontal should be determined using geometry before calculating the components.
  • There is a reiteration of the need to use trigonometric functions correctly, with one participant stating that cos(36) gives the x-component and sin(36) gives the y-component, questioning why this method is incorrect.
  • A later reply emphasizes that when resolving forces, the components must not exceed the magnitude of the original force and must form a closed triangle, reinforcing the vectorial nature of force resolution.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the correct method for resolving the force into its components, as there are multiple interpretations and approaches discussed. The confusion regarding the application of trigonometric functions and the geometric representation of forces remains unresolved.

Contextual Notes

There are limitations in the discussion regarding the assumptions made about angles and the coordinate system used for resolution. The participants do not clarify the definitions of the angles involved or the specific orientation of the coordinate system.

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[URgent!] quick question about resolving force

Homework Statement



Hello guys...

I have trouble resolving force into its y- components. Dont laugh. Please have a look on the photo I attached. The force is perpendicular to the slop, and the angle of the slope is given there. And then, what I did is just dot(extend the force), and then use sin(angle) to resolve the force into its component. Of course this is not right, so, why this is wrong. why?

Homework Equations

http://img860.imageshack.us/img860/513/xisu.png

Uploaded with ImageShack.us

The Attempt at a Solution

 
Last edited by a moderator:
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You are incorrectly calculating the force components...the force acts at what angle to the horizontal? (Use geometry). Then find the y component of the force using trig.
 


no, why is this incorrect? where did I mess up?
 


PhanthomJay said:
You are incorrectly calculating the force components...the force acts at what angle to the horizontal? (Use geometry). Then find the y component of the force using trig.

where did i mess up? horizontal is 36 degree, and cos 36 will give x, and sin 36 will give y. but why this is not right?
 


kougou said:

Homework Statement



Hello guys...

I have trouble resolving force into its y- components. Dont laugh. Please have a look on the photo I attached. The force is perpendicular to the slop, and the angle of the slope is given there. And then, what I did is just dot(extend the force), and then use sin(angle) to resolve the force into its component. Of course this is not right, so, why this is wrong. why?

Homework Equations




http://img860.imageshack.us/img860/513/xisu.png

Uploaded with ImageShack.us

The Attempt at a Solution


kougou said:
where did i mess up? horizontal is 36 degree, and cos 36 will give x, and sin 36 will give y. but why this is not right?

The last quote is pretty close to the answer. Now you just have to put an x-y coordinate system on the drawing (like with +x pointing right and +y pointing up), and give the x and y components of that vector in (x,y) coordinates.
 
Last edited by a moderator:


When you resolve a force into its components, none of the components can have a magnitude greater than the force itself.

If you always bear this in mind, then you will correctly sketch the triangle for resolution of forces without confusion.

The components must add together vectorially to equal the force.

They must form a closed triangle of forces: horiz comp + vert comp = force
 

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