What Causes Incorrect Section Placement in Static Equilibrium and Torque?

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SUMMARY

The discussion focuses on solving a static equilibrium problem involving a horizontal scaffold of length 2.00 m and mass 50.0 kg, suspended by two cables with a total paint can mass of 75.5 kg. The tension in the right cable is incorrectly stated as 780 N; the correct torque calculation should be 780 N multiplied by 2 m, resulting in 1560 Nm. The center of mass of the paint cans is determined to be 0.554 m from the right cable, requiring adjustments in the torque calculations to account for equilibrium conditions.

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itachipower
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Homework Statement


I have been trying to solve this problem for a while now and I can't figure out what I am doing wrong...

Here is the problem:

In the figure below, a horizontal scaffold, of length 2.00 m and uniform mass 50.0 kg, is suspended from a building by two cables. The scaffold has dozens of paint cans stacked on it at various points. The total mass of the paint cans is 75.5 kg. The tension in the cable at the right is 780 N. How far horizontally from that cable is the center of mass of the system of paint cans?

12-32.gif



Homework Equations



T = r x F

Sigma T = 0

The Attempt at a Solution



What I am doing is using the left cable as the rotational axis for Torque. So I get Torque due to the beam + torque due to the CoM of the paint cans = 780N

Therefore, (50)(9.8)(1m) + (75.5)(9.8)(x) = 780N

The answer is supposed to be .554 m. So I think I'm missing a force but I don't know what it is. Thanks for your help :)
 
itachipower said:

What I am doing is using the left cable as the rotational axis for Torque. So I get Torque due to the beam + torque due to the CoM of the paint cans = 780N

Therefore, (50)(9.8)(1m) + (75.5)(9.8)(x) = 780N

The answer is supposed to be .554 m. So I think I'm missing a force but I don't know what it is. Thanks for your help :)

Welcome to PF,Itachi (don't use sharingan on me) lol :wink:
The scaffold is in equillibrium.So,clockwise moment is equal to anticlockwise moment.You're 780N is wrong,it has to be the torque there.
780 x 2=1560Nm.
You are using the other cable as a reference point.So,you will get the distance from.Therefore,you have to subtract it from 2m. o:)
 
Welcome to PF,Itachi (don't use sharingan on me) lol :wink:
The scaffold is in equillibrium.So,clockwise moment is equal to anticlockwise moment.Your 780N is wrong,it has to be the torque there.
780 x 2=1560Nm.
You are using the other cable as a reference point.So,you will get the distance from.Therefore,you have to subtract it from 2m.o:)
 
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