Understanding Static Equilibrium in a Scaffold Setup

In summary, the problem involves a uniform plank resting on two horizontal bars of a scaffold with a painter standing on the overhanging part. The painter has a mass of 68.0 kg and the plank has a length of 6.00 m and a mass of 31.0 kg. The bars are 4.50 m apart and the overhang is 1.50 m. To find the maximum distance the painter can walk before the plank tips, an equation is used to describe equilibrium at the second scaffold, resulting in a distance of 0.684 m. The normal reaction at the other scaffold is not considered because it is not contributing to the equilibrium at the second scaffold.
  • #1
Kenny Lee
76
0
The problem is stated as follows:

A uniform plank with a length of 6.00 m and mass 31.0 kg rests horizontally across two horizontal bars of a scaffold. The bars are 4.50 m apart, and 1.50 m of the plank hangs over one side of the scaffold.
How far can a painter with a mass of 68.0 kg walk on the overhanging part of the plank before it tips?

Its a simple problem. We just fix up an equation that describes eqbm about the second scaffold (from the man and the center of mass) and we get a result of 0.684...

But I was wondering why we don't consider the normal reaction at the other scaffold? Shouldn't there be an upwards force contributing towards an ACW moment at that point... why don't we include it in calculations? I need help. Anyone please.
 
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  • #2
Because when the painter starts going at certain distance the Planck won't be supported by that scaffold, it'll start lifting, but still in equilibrium at a certain position of the painter in the Planck.
 
  • #3
Thanks for replying!

Yea, I think I get it now. thanks.
 

FAQ: Understanding Static Equilibrium in a Scaffold Setup

1. What is static equilibrium?

Static equilibrium refers to a state in which an object is at rest and all forces acting on the object are balanced, resulting in no net acceleration.

2. How is static equilibrium different from dynamic equilibrium?

Static equilibrium involves a stationary object, while dynamic equilibrium involves an object in motion at a constant velocity. In dynamic equilibrium, the forces acting on the object are balanced, but the object is still moving.

3. How do you determine if an object is in static equilibrium?

An object is in static equilibrium if the sum of all forces acting on the object is equal to zero and the sum of all torques (rotational forces) acting on the object is also equal to zero.

4. What are some real-life examples of static equilibrium?

Some examples of static equilibrium include a book resting on a flat surface, a ladder leaning against a wall, and a person standing still on the ground.

5. How can static equilibrium problems be solved?

To solve a static equilibrium problem, you need to draw a free-body diagram, identify all the forces and torques acting on the object, and then use Newton's laws of motion and the principles of moments to determine the unknown forces or angles.

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