Problem Introduction Animation
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Louis the Lamp is tired of his lonely existence up in the attic and attempts to escape through a trap door in the floor. He must determine which of the supports he should remove so that the door will open.

What is known:

  • The trap door is supported by a hinge and a bearing with a circular shaft on one side.
  • The other side is supported by a sliding bolt, which is equivalent to a bearing with a square shaft.

Hinge Diagram


What type of reaction forces and moments does each of the supports exert on the trap door?


  • Analyze the conventional methods by which rigid bodies are held stationary, or are held together.
  • Determine the type of forces and moments that these supports exert on a rigid body in reaction to externally applied loads.
  • There is not enough data to determine the exact magnitude of each reaction. Only determine the type of reaction.