# Homework Help: Tension problem calculate theta

1. Mar 8, 2015

### Ciaran

1. The problem statement, all variables and given/known data

A cylinder of radius R and mass m is lodged between cross pieces that make an angle θ with each other. The cross pieces of negligible mass are connected in point C, with lengths AC = BC = 2R and CD = CE = 3R. Determine the tension in the horizontal rope DE. You may assume smooth floor.
2. Relevant equations

3. The attempt at a solution
My starting point was to calculate theta, which would be twice the inverse tangent of 1/3. I also know that the weight of the mass m will partner a reaction force that is spread evenly between the two points of contact with the ground. However I'm not too sure where to go from here and any help would be much appreciated!

2. Mar 8, 2015

### vela

Staff Emeritus
A picture would be really helpful.

3. Mar 8, 2015

### Ciaran

[PLAIN]http://Screen [Broken][/PLAIN] [Broken] shot [/PLAIN] [Broken] [PLAIN]http://Screen [Broken][/PLAIN] [Broken] Shot 2015-03-08 at 19.06.54[/PLAIN] [Broken]
Here it is- I thought I'd attached it, sorry!

Last edited by a moderator: May 7, 2017
4. Mar 8, 2015

5. Mar 8, 2015

### vela

Staff Emeritus
Equilibrium problems always come down to summing forces and torques and setting the sums equal to zero. Consider the equilibrium of the cylinder and of one of the cross pieces.

How did you calculate $\theta$? I don't think it can be determined from the information given, and the tension you find will be a function of $\theta$.