A simply supported beam of length $l=2 \mathrm{~m}$ is subjected to a concentrated moment $M=150 \mathrm{~kNm}$ at a distance $l / 2$ from the left end as shown in the figure. The elastic-strain energy $U$ of the beam is given by the following expression:
$$U=\frac{M^{2} l}{48 E I}$$
The section modulus of the beam is $E I=25 \times 10^{5} \mathrm{Nm}^{2}$.
The absolute value of the slope of the beam at a distance $l / 2$ from the left end is $\_\_\_\_$ (rounded off to three decimal places).
