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pintsize131
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Homework Statement
A uniform plank of length 4.7 m and weight 207 N rests horizontally on two supports, with 1.1 m of the plank hanging over the right support (see the drawing). To what distance x can a person who weighs 454 N walk on the overhanging part of the plank before it just begins to tip?
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Homework Equations
tnet=0
Fnet=0
t=(radius)(F sin [tex]\theta[/tex])
I'm not exactly sure if there are any other equations, or even if these are the right equations- I'm just so confused. I assumed that "radius" in the torque equation was equal to "x" in the drawing, and that the force was the weight of the man.
The Attempt at a Solution
t1=(r)(F sin [tex]\theta[/tex]1)
r=t1/454 sin 90
t2=(r)(F sin [tex]\theta[/tex]2)
r=t2/454 sin 91
(I did this trying to figure out the torque that would cause the board to start to tip.)
Set the equations equal to one another:
t1/ 454 (sin 90) = t2/ 454 (sin 91)
t1/ 454 = t2/ 454 (sin 91)
454*(sin 91)*t1 = 454*t2
I hit a dead end here. I'm so lost. Please help.
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