Force of a hinge on a hinged beam

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Homework Help Overview

The problem involves a beam attached to a wall with a hinge, supported by a cable, and requires determining the horizontal component of the force exerted by the hinge. The beam's weight and the angles involved are key factors in the analysis.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the equilibrium conditions of net force and torque, with attempts to set up equations based on torque balance. There is uncertainty regarding the use of angles and the length of the beam, leading to questions about how to proceed without complete information.

Discussion Status

Some participants suggest focusing on the tension in the cable and summing moments about the hinge as a starting point. There is recognition of the need to clarify the use of trigonometric functions and the implications of missing information regarding the beam's length. Multiple interpretations of the problem setup are being explored.

Contextual Notes

Participants note the absence of the beam's length as a potential constraint in solving the problem. The discussion reflects a need to clarify assumptions regarding the forces acting on the beam and their respective points of application.

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Homework Statement

A 26.6 kg beam is attached to a wall with a hinge and its far end is supported by a cable. The angle between the beam and the cable is 90°. If the beam is inclined at an angle of theta=13.3° with respect to horizontal, what is the horizontal component of the force exerted by the hinge on the beam? (Use the 'to the right' as + for the horizontal direction.)

Hint: The Net torque and the Net Force on the hinge must be zero since it is in equilibrium.

What is the magnitude of the force that the beam exerts on the hinge?

(Image attached)

The Attempt at a Solution



I already knew that the net force and net torque would be zero, so I set clockwise and counter clockwise torque equal to each other

τcw = τccw
Fdsinθ = Fdsinθ

And this is where I ran into trouble. Length of the beam is never given. I'm not really sure what angles to use where, and while I know that the force the beam exerts on the wall/hinge is equal and opposite to what the wall/hinge exerts on the beam, I'm not sure how to find it.

To find the magnitude of force in the second half of the problem, you would just take magnitude = √(Fx^2 + Fy^2), correct?

Any advice?
 

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It is best to first find the tension force in the cable by summing moments about the hinge.. the beams weight acts at midpoint and moment is force times perpendicular distance.. Your sohcahtoa is off. Try again.
 
PhanthomJay said:
It is best to first find the tension force in the cable by summing moments about the hinge.. the beams weight acts at midpoint and moment is force times perpendicular distance.. Your sohcahtoa is off. Try again.

Okay, I understand that I need to use cos instead of sin, but I still don't understand what to do without the length of the beam.
 
Sum moments of the forces about the hinge. aybe you don't need to know thw beam length.
 

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