Equlibrium and Gravitational Force

[amie]

Homework Statement

In the figure below, a uniform beam of length 12.0 m is supported by a horizontal cable and a hinge at angle θ = 70°. The tension in the cable is 500 N.
(a) What is the gravitational force on the beam, in unit-vector notation?

(b) What is the force on the beam from the hinge, in unit-vector notation?

http://www.webassign.net/hrw/12-73.gif

Homework Equations

Torque = r x f

The Attempt at a Solution

The system is in equilibrium and so I assumed that the two should be the opposites of each other. My real problem, however is I have no idea how to calculate the Torque or the gravitational force without knowing the weight on the beam.

 

[PhanthomJay]

Homework Statement

In the figure below, a uniform beam of length 12.0 m is supported by a horizontal cable and a hinge at angle θ = 70°. The tension in the cable is 500 N.
(a) What is the gravitational force on the beam, in unit-vector notation?

(b) What is the force on the beam from the hinge, in unit-vector notation?

http://www.webassign.net/hrw/12-73.gif

Homework Equations

Torque = r x f

The Attempt at a Solution

The system is in equilibrium and so I assumed that the two should be the opposites of each other.

not true, sum moments to get reaction force

My real problem, however is I have no idea how to calculate the Torque or the gravitational force without knowing the weight on the beam.

But you are given the tension in the cable.