Statics - Show a massless stick feels forces along the stick

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SUMMARY

The discussion focuses on the mechanics of a massless stick within a static system, emphasizing that forces at the hinges must align along the stick to maintain equilibrium. When the stick is massless, the forces acting on it, such as tension, must be directed along its length to prevent movement. In contrast, when mass is introduced, forces can act at angles due to the influence of gravity, demonstrating that the direction of forces is not constrained to align with the stick. This distinction is crucial for understanding static equilibrium in physics.

PREREQUISITES
  • Understanding of static equilibrium principles
  • Familiarity with force vectors and their components
  • Knowledge of tension in massless structures
  • Basic concepts of gravity and its effects on objects
NEXT STEPS
  • Study the principles of static equilibrium in rigid body mechanics
  • Learn about vector decomposition and force resolution techniques
  • Explore the effects of mass on static systems and force distribution
  • Investigate real-world applications of tension in structures, such as bridges and cables
USEFUL FOR

Students of physics, engineers, and anyone interested in understanding the principles of static systems and force interactions in mechanics.

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Homework Statement


A stick is connected to other partrs of a static system by hinges at its ends. Show that a massless stick feels forces, at the hinges, that are directed along the stick. Then show if the stick is massive, the forces do not need to point along the stick.


Homework Equations





The Attempt at a Solution


I have no idea where to start or how I can write this out to prove it in every situation. For instance its obvious the the stick attached to a wall and then a block, with a force point away from the wall, that all the forces go with the stick (exactly like tension in a massless rope). Then when mass is introduced the force of gravity clearly offsets the forces felt. I can use the later for the second part, but how does one go about showing the first part in all situations?
 
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The key is that the system, including the stick, is static - i.e. the stick does not move.

So, draw a stick in space, and draw a couple of random force vectors at each end. What do the forces have to do for the stick to not move? It's not allowed to rotate or translate.

If the forces don't point directly down the stick, how can they balance?
 

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