Equilibrium. How to solve for four variables?

In summary, a uniform beam weighing 288 N and 3.12 feet long is attached to a wall with a hinge, with the other end supported by a wire making equal angles of 30° with the beam and wall. The tension in the wire can be found by setting up equations for the horizontal and vertical components of the forces and torque, and solving for T. The weight of the beam also contributes to the torque, but only the perpendicular components of tension and weight are considered. Unit conversions may be necessary.
  • #1
moose726
3
0

Homework Statement


One end of a uniform beam weighing 288 N and 3.12 feet long is attached to a wall with a hinge. The other end is supported by a wire making equal angles of 30° with the beam and wall.

(a) Find the tension in the wire.

(b) What is the horizontal component of the force of the hinge on the beam?

(c)What is the vertical component of the force of the hinge on the beam?

Homework Equations


[tex]\Sigma[/tex]F=0
[tex]\Sigma[/tex][tex]Torque[/tex]=0

The Attempt at a Solution


I drew a free body diagram of the beam and the components of the forces from tension and the hinge. From this I got four equations:
[tex]\Sigma[/tex]Fx = Fx-Tx = 0
[tex]\Sigma[/tex]Fy = Fy+Ty-mg = 0
[tex]\Sigma[/tex] Torque = 118.5+.4754Tx-.823Ty=0 (T is tension, this torque is with the hinge as the origin.)
Fy=Fxtan(30)
I'm not sure how to solve for each variable with these equations.
 
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  • #2
The easiest way to think about this is to break it into parts. Instead of solving for multiple unknowns just solve for part a.

The vertical component of tension must be perfectly balanced by the vertical component of the torque of the beam. Same goes for the horizontal tension.

You can calculate the torque in the x and y directions and then you have two equations with two unknowns.
 
  • #3
Take the components of tension T along and perpendicular to the beam. Similarly take the components of the weight of the beam, which acts at the center of the beam.
The perpendicular components contribute to the torque, while components along the beam does not contribute to the torque.
Apply the condition for equilibrium and solve for T.
Convert the unit of length from ft to m.
 

1. What is equilibrium and why is it important?

Equilibrium is a state where the rates of forward and reverse reactions are equal, resulting in no overall change in the system. It is important because it represents a stable state in a system and allows for prediction of the behavior of a reaction or system.

2. How do you calculate equilibrium constants?

The equilibrium constant, K, is calculated by dividing the concentration of products by the concentration of reactants at equilibrium. The concentrations must be in molarity (M) and the coefficients in the balanced chemical equation are used as exponents.

3. What factors can shift the equilibrium of a reaction?

Changes in temperature, pressure, and concentrations of reactants or products can shift the equilibrium of a reaction. Catalysts and changes in volume can also affect equilibrium.

4. How do you solve for four variables in an equilibrium equation?

To solve for four variables in an equilibrium equation, you must set up an ICE (initial, change, equilibrium) table. This involves determining the initial concentrations and changes in concentrations for each species in the equation, and then using these values to solve for the equilibrium concentrations.

5. How can Le Chatelier's principle be used to predict the effect of changes on equilibrium?

Le Chatelier's principle states that when a stress is applied to a system in equilibrium, the system will shift in a way that minimizes the effect of the stress. This principle can be used to predict the direction of equilibrium shift when changes are made to temperature, pressure, or concentrations of reactants or products.

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