# Reaction force on a leaned beam

1. Jan 27, 2015

### Karol

1. The problem statement, all variables and given/known data
A beam of 12[kN] is on a smooth floor on one side and on a rough edge on the other.
The total length of the beam is 10[m].
What is the reaction on the edge.

2. Relevant equations
Moments (torque): F1L1=F2L2

3. The attempt at a solution
I drew the forces. the reaction on the floor is vertical and also on the edge since there aren't horizontal forces.
Moments around point A:
$$12[kN]\cdot 5\cdot \cos 30^0=R\cdot\frac{4[m]}{\tan 30^0}\rightarrow R=7.5[kN]$$
In the book it's 6.5, i think it's a mistake

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2. Jan 27, 2015

### haruspex

I agree with 7.5kN.

Edit: looks like they took the horizontal distance for mg but the distance up the slope for the wall's reaction.
Edit 2: ... are you sure they wanted the total reaction, not just the normal reaction from the wall?

3. Jan 27, 2015

### Karol

I am almost sure they want the total reaction.
I leave this problem since i have another one, a little more problematic