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An object suspended by 2 strings

  • Thread starter crysland
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  • #1
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When two strings are used to suspend an object, is it possible for one or both of the angles to be zero (that is, one or both strings are horizontal to the ground) ? Why or why not? Deduce whether either of these scenarios is possible.

I say no, it's impossible but i really don't know how to explain this.
 

Answers and Replies

  • #2
Simon Bridge
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What happens if both the angles are zero?
 
  • #3
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the string is horizontal?
 
  • #4
Simon Bridge
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So draw a free-body diagram for the situation and work out the tensions in the strings.

Repeat for a string the makes an angle ##\theta## to the horizontal and another string horizontal.
 
  • #5
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When theta is 0, it means there's no force in the y direction.
 
  • #6
Simon Bridge
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When theta is 0, it means there's no force in the y direction.
So... can the horizontal strings hold the mass up?
 
  • #7
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No, it can't
 
  • #8
Simon Bridge
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Which makes sense - two horizontal strings are basically just the one string stretched between two walls. IRL if you hang a mass off the middle, the string will no longer be horizontal - it gets a v shape.

Now do the free-body diagram thing again, but, this time, one string is horizontal and the other forms an arbitrary angle to the horizontal.
 

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