(adsbygoogle = window.adsbygoogle || []).push({}); Torque/Static Equilibrium/Forces problem....

I have been working on this problem for a few hours, but I just can't get it ...

1. The problem statement, all variables and given/known data

Problem:

A 3.0-m-long rigid beam with a mass of 100 kg is supported at each end. An 80 kg student stands 2.0 m from support 1. How much upward force does support 1 exert on the beam?

here is an image:

http://photo.ringo.com/208/208651783O865465193.jpg [Broken]

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2. Relevant equations

τ=Frsinφ

F=ma

3. The attempt at a solution

I figured out the torques kinda, but do i use the mass as (2/3*100)+80? or (2/3*100)+40...either way i kept getting a wrong answer....

and the center of mass i assume is where the person is right? bec the 80kg addition would be the most massive point right?

since the angles are 90 degrees, the sine of φ doesnt matter right?, i mean it would only affect the sign +/- of the answer....since τ=Frsinφ, and φ is either 90 or -90 degrees...

idk...basically i just cant get this...

i got solutions ranging from 76.666.., 1306.666... etc...

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# Homework Help: Torque/Static Equilibrium/Forces problem

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