Simple Counter-balance/Counter-weight Calculation Problem

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Discussion Overview

The discussion revolves around calculating the necessary counterweight for a pole stand with an object hanging from it, focusing on torque and balance. Participants explore the implications of different configurations of counterweights and the effects of the pole's mass on stability, including the ability to rotate an object around the pole without flipping it.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant suggests that the problem is a simple torque calculation and proposes mapping all mass onto a horizontal plane, assuming a rigid pole frame with no mass.
  • Another participant questions the scenario when the pole frame has mass, providing specific weights for various components and inquiring about the stability of different counterweight configurations.
  • A later reply emphasizes the importance of drawing a plan view to identify centers of mass and fulcrum lines, suggesting that static balance calculations should consider potential overbalance during rotation.
  • Concerns are raised about the stability of the proposed cases under different angles of rotation, with one participant expressing doubt about the effectiveness of Case #2 compared to Case #1.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the effectiveness of the counterweight configurations or the implications of the pole's mass. Multiple competing views remain regarding the stability of the setups under different conditions.

Contextual Notes

Participants note the need for assumptions about the rigidity of the pole and the distribution of mass, as well as the potential for dynamic effects when the object is rotated. Specific calculations and torque values are not provided, leaving some mathematical steps unresolved.

Who May Find This Useful

This discussion may be useful for individuals interested in mechanics, particularly those dealing with torque, balance, and stability in physical systems involving counterweights.

rh2022
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Hi, I am trying to figure out how much weight is needed to counter balance a pole stand where an object(m kg) is hanging. I also want to know which is more effective way to place counterweight as shown in the picture below. I was wondering if the counterweight A, B, and C are equal.

It seems to be a simple torque problem, but I am a bit confused as the pole is not a straight line.
Any help would be appreciated.

counterweight-problem.jpg
 
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Welcome to PF.
It is a simple torque problem.
Map all the mass onto the horizontal plane.
Assume the pole frame is rigid and has no mass.
Assume the diagonal line is the fulcrum = hinge line.
Case #1: A = B = 10 kg. A + B = 20 kg.
Case #2: C = 20 kg.
 
Thank you for your reply.
I have an additional question.

What if the pole frame has mass: pole frame = 50kg, pole arm = 30kg, base frame = 20kg, base legs = 20kg each. Does it make difference?
I want the green object X(20kg) rotate/swing 360 degree around the Pole Frame without flipping it.
Do you think both Case #1 and Case #2 should provide stable support if I place a 20kg+ counter weight at the end base leg frame?
counterweight-problem_2.jpg
 
rh2022 said:
I want the green object X(20kg) rotate/swing 360 degree around the Pole Frame without flipping it.
You must draw the plan view, then mark all the centres of mass.
Identify the possible fulcrum line for each situation.
From that you can work out the total torque for different rotation angles.
You are considering only the static balance, do not spin it rapidly.
Note that when it starts to overbalance it will accelerate rapidly.

I expect case #2 will fail at some angle well before 135°.
Case #1 may be more secure, but you must do the numbers.
 
Last edited:

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