Finding the radius for torque from a cable

[PhizKid]

Homework Statement

Homework Equations

Torque = Force * radius * sin(angle)

The Attempt at a Solution

I am trying to find the radius for the torque of the cable, but I can't seem to use any trig to solve for that side in terms of L.

 

[gsmith]

The radius is L,
you do not need any trigonometry.
remember, radius (when referring to torque) is defined as the distance from the pivot point to the point that the force is acting on - in other words - L.

 

[PhizKid]

The pivot point to the point that the force is acting on is marked in my diagram by 'R'. I don't see how R = L

 

[gsmith]

The wire is pulling on the beam with a tension, this is the force in question. The point that you have marked as the point that the force is acting upon is on the wire itself. In order to cause a torque on the beam the force must be acting on the beam itself, not the wire.

 

[PhizKid]

I don't understand what you are saying. The force of the Tension is acting on the beam. The axis of rotation is the hinge. So, we need the distance from the Tension to the axis of rotation. To do that, we use the perpendicular distance created from the axis of rotation to the Tension. Isn't that what we want?

 

[TSny]

You have a right triangle where L is the hypotenuse and R is the side opposite the 30-degree angle. What trig function relates side opposite and hypotenuse?

 

[PhizKid]

Ah, I see the sine function now. Thanks