# Equilibrium from the ceiling. Solve using cosines

1. Jan 22, 2010

### tigerwoods99

thanks

Last edited: Jan 23, 2010
2. Jan 22, 2010

### Redbelly98

Staff Emeritus
Where is the center of the rod located, relative to point B?

3. Jan 22, 2010

### tigerwoods99

I'm sorry!

Last edited: Jan 23, 2010
4. Jan 22, 2010

### Redbelly98

Staff Emeritus
Yes, I realize that the rod is opposite to angle B. The question was meant to give you a clue about the configuration. So more specifically, what do we know about where the center-of-mass of the hanging rod is located, relative to the point B from which the rod and strings are hung?

5. Jan 22, 2010

### tigerwoods99

I think the mg of the rod is located directly underneath point B where it is hung from the ceiling

6. Jan 22, 2010

### Redbelly98

Staff Emeritus
Yes, exactly. You can use that information to figure out the angle the rod makes with the horizontal.

7. Jan 22, 2010

### tigerwoods99

Ok. so knowing that does angle B "split" into two halves. I am still not sure where this is taking me.!!

8. Jan 22, 2010

### Redbelly98

Staff Emeritus
Draw a vertical line from B to the rod center. The triangle is split into two smaller ones. Solve either of the smaller triangles.

Good luck!

9. Jan 22, 2010

### tigerwoods99

Ok thanks! I think i still need a little more guidance on this though. What will this solve? How will this help find theta?

10. Jan 23, 2010

### Redbelly98

Staff Emeritus
The key is to find the triangle's angle located at the center of the rod. If you haven't already, draw a figure including the vertical line between B and the rod center.

11. Jan 23, 2010

### tigerwoods99

Ok. thanks

Last edited: Jan 23, 2010