What is the Minimum Height for Anchoring the Cable to the Wall?

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Homework Statement


A 66 kg sign hung centered from a uniform rod of mass 8.2kg and length 2.3m. At one end the rod is attached to the wall by a pivot; at the other end it's supported by a cable that can withstand a maximum tension of 800 N. what is the minimum height h above the pivot for anchoring the cable to the wall?



Homework Equations



Not entirely sure if these apply.

\tau = r x F
\tau = \Sigma

The Attempt at a Solution



Mg = (74.2)(9.8) = 727.16 N (Total Fy)

\tau = (2.3)*(727.16) = 1672.5

After I get this information I'm lost.
 
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Hi SpeedPhysics ! Welcome to PF! :smile:
SpeedPhysics said:
A 66 kg sign hung centered from a uniform rod of mass 8.2kg and length 2.3m. At one end the rod is attached to the wall by a pivot; at the other end it's supported by a cable that can withstand a maximum tension of 800 N. what is the minimum height h above the pivot for anchoring the cable to the wall?

Mg = (74.2)(9.8) = 727.16 N (Total Fy)

\tau = (2.3)*(727.16) = 1672.5

(it's not 2.3 … the weight goes through the centre :wink:)

ok, that's the torque (the moment) of the weight …

now, if you call the tension T, what's the torque of the tension? :smile:
 
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