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Simple resolution of forces

  • Thread starter edsys89
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  • #1
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Homework Statement


A bag of sand weighing 100 N is hanging on the end of a long, light rope. The bag is pulled to one side by a horizontal force so that the rope makes an angle of 250 with the vertical. Find the magnitudes of the horizontal force and the tension in the rope.


The Attempt at a Solution



I know that the horizontal force makes an angle of 1150 to the rope.
I know that the magnitude of the horizontal force + the force on the rope equal 100N.
I'm stuck on which way to go. Some sort of pendulum formula?
 

Answers and Replies

  • #2
HallsofIvy
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The bag still weighs 100N so there is a force of 100N straight down: that is -100 j. There is an unknown force Xi. The sum of those two forces is Xi- 100j and, because the only off setting force is the tension in the rope, at 25 degees with the vertical, if we call the tension "T", that vector is T sin(25)i- T cos(25)j. Set those equal and you have two equations to solve for X and T.
 
  • #3
PhanthomJay
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Homework Statement


A bag of sand weighing 100 N is hanging on the end of a long, light rope. The bag is pulled to one side by a horizontal force so that the rope makes an angle of 250 with the vertical. Find the magnitudes of the horizontal force and the tension in the rope.


The Attempt at a Solution



I know that the magnitude of the horizontal force + the force on the rope equal 100N.
Why do you say this? Draw a free body diagram of the bag, identifying all forces acting on it, and the direction of those forces. Then apply Newton 1 in the x and y directions.
 

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