Calculating Tension of a bob moving in horizontal circles

  • #1
Could someone please look at the problem below and see if i am on the right lines of solving it? I am finding the whole subject of circular motion hard to get my head around and therefore not 100% confident in my workings. I have also attached my free body diagram.

Homework Statement



Calculate the tension in a 3m string attached to a 3kg bob that is moving in horizontal circles of 0.6m radius

Homework Equations



Tanθ = Opposite/Hypotenuse

TCosθ = mg

The Attempt at a Solution



θ = Tan-1 0.6/3
θ = 10.32°

TCosθ = mg
T = mg/Cosθ
T = (3Kg x 9.81) / Cos 10.32
T = 29.91 N
 

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Answers and Replies

  • #2
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θ = Tan-1 0.6/3
The radius over the hypotenuse would equal sinθ, not tanθ.

Other than that, you're doing fine.
 
  • #3
The radius over the hypotenuse would equal sinθ, not tanθ.

Other than that, you're doing fine.
Thanks for that i have just noticed i used TAN not SIN for my workings myself which obviously changes my final answer slightly. Thanks for the reassurance i'm on the right track. I have spent many long hours trying to get my head around this whole subject.
 

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