Answer:
98.1 N
Step-by-step explanation:
We assume that the weight of the beam acts at its center.
Mass m = 20 kg
Weight = mass x acceleration due to gravity 9.81 m/s^2
Weight = 20 x 9.81 = 196.2 N
Lenght of beam = 4.0 m
Taking moment about the wall
Moment is force x perpendicular distance
196.2 x 2 = T x 4
392.4 = 4T
T = 392.4/4 = 98.1 N.
See force diagram below.