Question

The uniform 100-kg I-beam is supported initially by its end rollers on the horizontal surface at A and B. by means of the cable at C, it is desired to elevate end B to a position 3 m above end A. Determine the required tension P, the reaction at A, and the angle q made by the beam with the horizontal in the elevated position.

Answer 1

I attached a free body diagram for a better understanding of this problem.

We start making summation of Moments in A,

$\sum M_A = 0$

$P(6cos\theta)-981(4cos\theta)=0$

$P=654N$

Then we make a summation of Forces in Y,

$\sum F_y = 0$

$654+R-981 = 0$

$R=327N$

At the end we calculate the angle with the sin.

$sin\theta = \frac{3m}{4m+2m+2m} = \frac{3m}{8m}$

$\theta = 22.02\°$