Solving Lever (Moment) Homework Problem

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SUMMARY

The discussion revolves around a physics problem involving a uniform 10 m long, 50 kg pole and the application of forces to maintain its horizontal position. The pole's weight is calculated to be 500 N, and one individual applies an upward force of 100 N. To keep the pole horizontal, a second individual must exert an upward force of at least 400 N at a specific distance from the fulcrum, which is the first individual lifting one end of the pole. The key to solving the problem lies in understanding moments and the distribution of forces along the pole.

PREREQUISITES
  • Understanding of basic physics concepts, particularly moments and equilibrium.
  • Knowledge of force calculations, including weight and upward forces.
  • Familiarity with the concept of a fulcrum in lever systems.
  • Ability to apply the principle of moments to solve problems involving levers.
NEXT STEPS
  • Study the principle of moments in physics, focusing on lever systems.
  • Learn how to calculate forces and distances in equilibrium scenarios.
  • Explore examples of similar physics problems involving levers and fulcrums.
  • Practice solving problems that require balancing forces and moments in static systems.
USEFUL FOR

Students studying physics, particularly those focusing on mechanics and equilibrium, as well as educators looking for examples of lever problems in teaching materials.

luysion
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Homework Statement


A uniform 10 m long, 50 kg pole is lying on the ground. You get your little brother to lift at one end with an upward force of 100 N. How far from the other end will you need to lift so the pole stays horizontal (in m)? [Hint: Using your little brother as the fulcrum, what upward force, in N will you need to apply?]


Homework Equations





The Attempt at a Solution



Hi, I am really confused as to how to answer this. I know its to do with moments but i don't understand how to use the brother as the fulcrum because how much force does the other brother have to apply? the question doesn't say
 
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I think this is a poorly conceived question.
The other brother must lift with at least a force that will, when combined with the first brother, equal the weight of the the pole. In round figures (taking g as 10m/s²)
The weight is 500N and the one guy has an upward force of 100N, so you need at least 400N upwards. The question is, where do you apply that 400N to keep the pole horizontal; that is, there is no overall turning moment.
(At least that's what I think they mean!)
 

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