Solving for Seesaw Balance: Mass and Distance Relationship

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SUMMARY

The discussion addresses a seesaw balance problem involving two children with masses of 20.0 kg and 28.0 kg on a 3.0 m long seesaw. The fulcrum is positioned at the midpoint, and the effective riding position is determined by the principle of moments, where the weight times distance from the fulcrum must be equal on both sides. The solution reveals that the child with a mass of 20.0 kg must sit 2.14 m from the fulcrum to balance the seesaw, while the 28.0 kg child sits at the end.

PREREQUISITES
  • Understanding of torque and moments in physics
  • Familiarity with the equations of mechanical advantage (MA) and ideal mechanical advantage (IMA)
  • Knowledge of weight (W) and force (F) relationships
  • Basic algebra for solving equations
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  • Study the concept of torque and its application in rotational equilibrium
  • Learn how to apply the principle of moments in various mechanical systems
  • Explore the equations of mechanical advantage in simple machines
  • Practice solving similar problems involving seesaws and lever systems
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Students studying physics, educators teaching mechanics, and anyone interested in understanding the principles of levers and balance in simple machines.

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[SOLVED] Simple Machines Proble,

Homework Statement


Two kids are riding on a seesaw that is 3.0m long with its fulcrum exactly in the middle. When one end touches the ground, the other end is 1.4m in the air. If one child has a mass of 20.0kg and the other is 28.0kg, which child sits at the end of the seesaw and how far in does the other child sit so they can ride the seesaw effectively? Assume 100% efficiency for the seesaw.



Homework Equations

[I'm not sure if all these are needed, but these are the equations we were given in this unit]
Wi = Fi x Di
Wo = Fo x Do
MA = Fo / Fi
IMA = Di / Do
%eff = Wo / Wi or MA / IMA



The Attempt at a Solution


Umm I know from class that the answer is x = 2.14 m , but I don't know how to get there.
The stuff I attempted is majorly messed. I know it's wrong but I have no clue what to do. I basically found the Di and Do for each kid and subtracted them or something. I'm not even sure anymore. Lol..
 
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When is the seesaw ridden effectively? Is that related to total moment about the fulcrum in any way?
 
When Fo is greater than Fi?
That might be it.

*edit* JUST KIDDING! It's actually that Wo has to be equal to Wi.
 
Last edited:
Right, but have you understood?
 
Lol, I guess I do now that I figured that out. Nevermind!
 

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