Introductory Torque Statics Problem

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SUMMARY

The discussion centers on solving a torque statics problem involving a 4.0-meter-long, 24 kg pole. The user applies the torque equilibrium equation, ∑τ=0, and attempts to calculate the force exerted at a specific point on the pole. The calculations lead to an unexpectedly high force value of -1344 N, prompting questions about the application of torques and the choice of pivot point. The user is advised to reconsider the pivot point and the distribution of weight to achieve a correct solution.

PREREQUISITES
  • Understanding of torque and static equilibrium principles
  • Familiarity with the equation ∑τ=0 for torque calculations
  • Knowledge of how to identify pivot points in statics problems
  • Basic skills in applying forces and weights in physics problems
NEXT STEPS
  • Review the concept of torque and its applications in static equilibrium
  • Learn how to effectively choose pivot points in torque problems
  • Study the implications of weight distribution in statics
  • Practice solving similar torque statics problems for better understanding
USEFUL FOR

Students studying physics, particularly those focusing on statics and torque problems, as well as educators looking for examples of common mistakes in torque calculations.

JSmithDawg
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Homework Statement


You're carrying a 4.0-m-long, 24kg pole to a construction site when you decide to stop for a rest. You place one end of the pole on a fence post and hold the other end of the pole 35 cm from its tip.

I've drawn a diagram of the problem on Paint...
upload_2015-2-9_19-15-51.png


Homework Equations


∑τ=0
τ=F⊥r

The Attempt at a Solution


I know that ∑τ=F(r1)+w(r2)+N(r3)=0, and I'm going to rewrite it so F(r1)+N(r3)=-w(r2). Now, if I call the left-most point the pivot point, my new equation becomes F(.35m)+4m(9.8 N/kg * 24kg) =-2m(-9.8 N/kg* 24 kg), which simplifies to F(.35m) = -470.4Nm, which makes F=-1344N. This seems way too big to be right; what did I do wrong?
 
Physics news on Phys.org
it would be much easier to use the RIGHTmost point as the pivot. Where is the weight applied? ... why are you not adding torques to zero? ...
 

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