# Displacement in a frame

1. Feb 10, 2017

### fonseh

1. The problem statement, all variables and given/known data
I know that when the 80kN act on B , the frame will be dispalced by Δ1 to the right .. When the 40kN act on C , the frame will be displaced Δ2 to the right ... Why the author use Δ1 + Δ2 for C ?

2. Relevant equations

3. The attempt at a solution
Is the author wrong ? I think the author should use Δ2 at C instead of Δ1 + Δ2 for C , am i right ? Δ1 can / cannot be the same as Δ2

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2. Feb 10, 2017

### haruspex

The two horizontal loads are applied together. The author chooses to define Δ2 as C's additional displacement beyond that of B.
Do you have an issue with an equation based on that?

3. Feb 10, 2017

### fonseh

why The author chooses to define Δ2 as C's additional displacement beyond that of B ? why cant the author define the displacement at C = Δ2 only ??

4. Feb 10, 2017

### haruspex

If you follow through the equations, some of them turn out simpler with the author's choice. Whether it is simpler overall I have not tried to determine.