
Explanation:
Given data:
mâ = mass of crate = 151.5 kg
mâ = mass of the boom = 74.9 kg
g = acceleration by gravity = 9.81 m/s²
L = length of the boom
θ = angle of the boom to the horizontal
Ď = Â angle of the cable to horizontal
Solution:
From image you can see that
tan (θ) = 6/12 = 0.5
so
θ = arctan(0.5)= 26.57°
From the image you can see that
tan(Ď) = 3/12 = 0.25
so
Ď = arctan(0.25) = 14.04°
As the system is in equilibrium so the magnitude of clockwise torque must be equal to anticlockwise torque. so
mâĂgĂcos(θ)ĂL/2 + mâĂgĂcos(θ) L = TĂsin(θ+Ď)ĂL
(mâ/2 + mâ)ĂgĂcos(θ) = TĂsin(θ+Ď)
T = (mâ/2 + mâ)ĂgĂcos(θ) / sin(θ + Ď)
T = [(151.5 kg)/2 + (74.9 kg)]Ă(9.81 m/s²)Ăcos(26.57°)/ sin(26.7°) + (14.04°))
T = 2023.28 N