# Statics - Compression and tension forces in a truss

• jacobthejones

## Homework Statement

I am trying to find the forces in KJ, CJ, and CD.

ΣFx=0

## The Attempt at a Solution

I found the magnitude of KJ to be 26.8kN, which is correct (according to answers in the back of the book). I believe it is a compressive force. The book lists all 3 forces as tension.

If all 3 members were under tension, there would have to be a reactionary horizontal force external to these three members acting on the right side of the truss to maintain equilibrium. Because there is no reactionary force with a horizontal component on the right side, the three members cannot all be experiencing tension. Therefore, the book has a typo and either one or two of the members are experiencing a compressive force.

Is this logic correct?

#### Attachments

• Untitled.png
9.7 KB · Views: 5,226
Last edited:

## Answers and Replies

I would agree.
If all three of those are tensions, then there would be positive tension across the length of the truss and the anchor points (A and G) would not be simple vertical supports.

I confirm. I get 26.8 N compression in KJ and 10.8 N tension in CJ.