There is an 80kg beam attached to a hinge on a wall and supported by a cord. The angle between the cord and the beam is 25 degrees. The beam is 4.5m long., and the cord is attached to the beam a metre from the beam's end. There is a 20kg beam hanging from the very tip of the beam. Find the cord tension and the force exerted by the hinge.(adsbygoogle = window.adsbygoogle || []).push({});

CW Torque=(80kg)(9.8m/s^2)(2.25m)+(20kg)(9.8m/s^2)(4.50m)

=2646Nm

Since the torques must balance:

2646Nm=F(3.5m)

F=756N

Plug this into the right triangle created by the cord and the beam:

Tension in the cord=cos65/756N=1790N

Now here's where I have the trouble. How do I get the force exerted by the hinge? I found the x xomponent, which is 1790sin65. But when I use this answer to find the force vector of the hinge, I don't get the right answer.

(1790sin65)(sin25)=687N. The answer is 1600N. Where have I gone wrong?

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# Homework Help: Beam Torque Problem

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