What is the Tension in the String and the Mass of the Bar?

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The discussion focuses on calculating the tension in a string supporting a horizontal bar and determining the mass of the bar. The tension is initially presumed to be 19.6 N, corresponding to the weight of the 2 kg mass. However, confusion arises when attempting to resolve the forces vertically, leading to an incorrect calculation for the bar's mass. The participant struggles with applying the correct principles, such as moments and work done, to find the mass of the bar, which should be approximately 3.5 kg. Clarification on the pivot point and the correct use of equations is needed to resolve the problem accurately.
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Homework Statement


The bar is maintained horizontal & in equilibrium by an angled string which passes over a pulley and which carries a mass of 2kg at it's free end.

1) Calculate the Tension T in the String

2) Show that the mass of the bar is approximately 3.5kg

Homework Equations



-

The Attempt at a Solution



Included the picture there, it's a really easy question I guess but i think I'm missing something :confused:, or not understanding something very well...

for 1) I presume it's simply 19.6 N , the weight of the mass.

2) I'm a bit stuck here, what does it want you to use? If 19.6 in the tension in the string and you resolve it vertically I get 19.6cos 30 = 16.97 N which obviously doesn't work out to be 3.5kg, I think I'm missing something regarding the pivot, or maybe it's related to work done...

Any help would be great, it's just a stupid problem! :P

Edit: Using that work done thing - I got

(0.8 * 3.5) / cos (30) = 3.23 but still that's far off, so i don't think it can be that
 

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=P thanks
 

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