Solve Equilibrium Problem: Painter & Scaffold

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Homework Help Overview

The problem involves a painter standing on a scaffold, requiring the calculation of reaction forces at the supports of the scaffold. The scenario includes a painter, a supply of paint, and the weight of the scaffold itself, with specific distances provided for each component.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the application of Newton's laws and the concept of equilibrium. There is an exploration of the axis of rotation and how it affects the calculation of torques. Some participants express uncertainty about their calculations and seek clarification on the correct approach to finding the reaction forces.

Discussion Status

The discussion is active, with participants attempting calculations and seeking feedback on their reasoning. Some guidance has been offered regarding the consideration of torque and the placement of forces, but there is no explicit consensus on the final values of the reaction forces.

Contextual Notes

Participants are working within the constraints of a homework assignment, which may limit the information they can use or the methods they can apply. There is an ongoing examination of the assumptions related to the forces acting on the scaffold.

kee23
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Homework Statement


A 62.5kg painter stands 1.35m from one end of a 45.0 kg scaffold that is 4.50m long. She has 11.0kg supply of paint 1.00m from the end she is nearest to. Find the reaction forces at the supports if the scaffold is supported at each end.

Homework Equations



F=ma
N1+N2-w(mg)=0

The Attempt at a Solution


Well I know that sum of forces equal to zero and the Newton's second law formula F=ma. So I thought of calculating all the weights to get force (N) and then I got stuck. Please help me on this.
 
Last edited:
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Hint: Is the system rotating?
 
Yes, so the axis of rotation I choose in the left end of scaffold so the right end point will go counter clockwise (+) direction? Also I placed the painter on end of left side of scaffold as well.

http://img404.imageshack.us/img404/7128/equilibrium.png . Here's the diagram I drew.
 
Last edited by a moderator:
Fpainter= (62.5kg*9.81m/s)= 613.125N
Fsupply= (11.0kg*9.81m/s)= 107.91N
Fstands= 45.0kg*9.81m/s) = 441.45N
Total force Fpainter+Fsupply+Fstands= 1162.485N = N1+N2
Then 613.125N*1.35m+107.91*1.00m/4.50m= N2= 207.9175N
N1+N2= 1132.485N+207.9175N= 1370N
so am I got it right? I don't get it. Please help
 
Then 613.125N*1.35m+107.91*1.00m/4.50m= N2= 207.9175N
In this equation you have left one term.
F(stand) acts at the center of the scaffold. So the torque due to this force is
45.0kg*9.81m/s) *2.25m.
Now find N2.
 
I got N2 as 429N. Do I add N1(1132.485N)? or subtract to get the other force?

EDIT: Nevermind, I got it. I had the Total force calculation got wrong. Thank you!
 
Last edited:

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