Answer:
W = 1,176 10⁴ J
Step-by-step explanation:
Work is defined by
W = F . d
bold indicates vectors
W = F d cos θ
In this case we must find the force to raise the load and the branch, suppose that the rate of rise is constant, this is the most common case
Σ F = 0
F - W₁ - W₂ = 0
where W1 is the weight of the branch and w2 wl weight of the load
F = (m₁ + m₂) g
This force is directed upwards and the displacement is upwards, therefore the angle is zero and the cos 0 = 1
we substitute in the work equation
A = (m₁ + m₂) g d
let's calculate
W = (40 + 20) 9.8 20
W = 1,176 10⁴ J
This is the work done by the external force