# Hanging sign problem

1. Nov 22, 2004

### strugglin-physics

A shop sign weighing 206 N is supported by a uniform 132 N beam of length L = 1.89 m as shown in figure below.

The guy wire is connected D = 1.19 m from the backboard. Find the tension in the guy wire. Assume theta = 43.0 o
Find the horizontal force exerted by the hinge on the beam.
Find the vertical force exerted by the hinge on the beam. Use "up" as the positive direction.

I get T = -mg * 1/2L + T*L*sin(43) = T = mg/2sin(40)

Fx = Hx -T cos(43) = 0
Hx = T cos(43)
Fy = Hy -mg + Tsin(43) = 0
Hy = mg - Tsin(43)

But these are incorrect. Where did I go wrong?

#### Attached Files:

• ###### gian0959.gif
File size:
5.5 KB
Views:
116
2. Nov 22, 2004

### arildno

"I get T = -mg * 1/2L + T*L*sin(43) = T = mg/2sin(40)"

This is complete nonsense!

You have 3 forces creating torques about the hinge. Which, and where do they act?

3. Nov 22, 2004

### strugglin-physics

That wasn't suppose to be torque but rather tension.

4. Nov 22, 2004

### arildno

It's still nonsense, since your units don't match (T and TL have not the same units)