Basic mechanics question -- Two cables supporting a stage light

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SUMMARY

The discussion centers on solving a mechanics problem involving two cables supporting a stage light, specifically from the OCR curriculum. The correct solution for the force exerted by the cables is 120N in the opposite direction to the weight of the light. The user initially struggled with calculations using scale drawings and vector methods but ultimately received guidance on summing forces to arrive at the solution.

PREREQUISITES
  • Understanding of basic mechanics principles, specifically force vectors.
  • Familiarity with the head-to-tail method for vector addition.
  • Knowledge of trigonometric functions, particularly cosine, in relation to angles in vector problems.
  • Ability to interpret and apply Newton's laws of motion.
NEXT STEPS
  • Study vector addition techniques, focusing on the head-to-tail method.
  • Learn about resolving forces into components using trigonometric functions.
  • Explore Newton's laws of motion and their applications in static equilibrium problems.
  • Practice similar mechanics problems from the OCR curriculum to reinforce understanding.
USEFUL FOR

This discussion is beneficial for students studying physics, particularly those preparing for OCR exams, as well as educators seeking to clarify mechanics concepts related to forces and equilibrium.

Krashy
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Homework Statement



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Homework Equations


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apparently none

The Attempt at a Solution


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Hi, this is a question from the OCR for self studying purposes. Only the first question is relevant for me. I know that the solution is 120N in the opposite direction to the weight, but i can't get to this solution. There is no calculation in the solution so i tried doing it with scale drawing and the head to tail method, but it didnt work. I also tried to multiply the 120N by the stage light with the cosine of the angle between the vectors but the angles are above 90 degrees so i won't get a useful solution.

All the other questions in that topic were really easy so i guess its something fairly simple that i need to do. I hope someone can help me. Thank you very much in advance.
 

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Hi Krashy and welcome to PF.

What is the sum of all the forces? Hint: Note that the resultant that you seek, when added to the 120 N down, should give you that sum.
 
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I got it, thanks again
 

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