Explanation:
Torque is the cross product of the radius vector and force vector.
τ = r × F
The magnitude of the torque is the force times the perpendicular distance. In other words, it is the force times distance times the sine of the angle between them.
τ = F r sin θ
Summing the moments where the beam meets the wall:
∑τ = Iα
(-20 N) (3 m) + (T sin 70°) (1.5 m) = 0
(T sin 70°) (1.5 m) = 60 Nm
T sin 70° = 40 N
T = 42.6 N
The answer cannot be 130 N, unless there is a mistake in the question.
