Another Statics problem with friction

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SUMMARY

The discussion focuses on a statics problem involving two wedges used to position a 400-lb block, with a coefficient of static friction of 0.25. The participant calculated the force P required to move the wedge, initially arriving at 273 lb instead of the correct value of 313 lb. The error was attributed to miscalculating the forces acting on the top wedge, specifically neglecting the normal force against the wall and the friction force. The analysis involved free body diagrams (FBDs) to sum forces in the vertical direction.

PREREQUISITES
  • Understanding of static friction and its coefficient
  • Proficiency in drawing and analyzing free body diagrams (FBDs)
  • Knowledge of force summation in static equilibrium
  • Familiarity with basic statics principles in mechanical engineering
NEXT STEPS
  • Study the principles of static equilibrium in mechanical systems
  • Learn about the calculation of normal forces in wedge problems
  • Explore advanced applications of friction in engineering contexts
  • Review examples of free body diagram analysis for complex systems
USEFUL FOR

This discussion is beneficial for students in mechanical engineering, particularly those studying statics, as well as professionals involved in structural analysis and design who require a solid understanding of friction and force interactions in static systems.

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Homework Statement


Two 10* wedges of negligible weight are used to move and position the 400-lb block. Knowing that the coefficient of static friction is 0.25 at all surfaces of contact, determine the smallest force P that should be applied as shown to one of the wedges.

Homework Equations


I broke the 400lb block with wedge touching it up from the wedge on the ground. I've got two FBD's I analyzed. Considering the 400lb block I summed forces in y to find Fn2. Then I considered the wedge to find P.

The Attempt at a Solution


The attachment has my solution. P should be 313lb I got 273lb.
 

Attachments

I figured this out long ago. The term is officially over. Thanks though!I was analyzing the top wedge wrong. I forgot about the force normal to the wall and the friction force against the wall.
 

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